Index: lld/COFF/PDB.cpp
===================================================================
--- lld/COFF/PDB.cpp
+++ lld/COFF/PDB.cpp
@@ -20,7 +20,6 @@
 #include "llvm/DebugInfo/CodeView/TypeDumpVisitor.h"
 #include "llvm/DebugInfo/CodeView/TypeStreamMerger.h"
 #include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
 #include "llvm/DebugInfo/MSF/MSFCommon.h"
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
@@ -34,6 +33,7 @@
 #include "llvm/DebugInfo/PDB/Native/TpiStream.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStreamBuilder.h"
 #include "llvm/Object/COFF.h"
+#include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/FileOutputBuffer.h"
 #include "llvm/Support/Path.h"
@@ -93,9 +93,9 @@
     if (Data.empty())
       continue;
 
-    msf::ByteStream Stream(Data);
+    BinaryByteStream Stream(Data);
     codeview::CVTypeArray Types;
-    msf::StreamReader Reader(Stream);
+    BinaryStreamReader Reader(Stream);
     // Follow type servers.  If the same type server is encountered more than
     // once for this instance of `PDBTypeServerHandler` (for example if many
     // object files reference the same TypeServer), the types from the
@@ -137,9 +137,9 @@
   if (Data.empty())
     return;
 
-  msf::ByteStream Stream(Data);
+  BinaryByteStream Stream(Data);
   CVSymbolArray Symbols;
-  msf::StreamReader Reader(Stream);
+  BinaryStreamReader Reader(Stream);
   if (auto EC = Reader.readArray(Symbols, Reader.getLength()))
     fatal(EC, "StreamReader.readArray<CVSymbolArray> failed");
 
@@ -161,9 +161,9 @@
 
 static void addTypeInfo(pdb::TpiStreamBuilder &TpiBuilder,
                         ArrayRef<uint8_t> Data) {
-  msf::ByteStream Stream(Data);
+  BinaryByteStream Stream(Data);
   codeview::CVTypeArray Records;
-  msf::StreamReader Reader(Stream);
+  BinaryStreamReader Reader(Stream);
   if (auto EC = Reader.readArray(Records, Reader.getLength()))
     fatal(EC, "Reader.readArray failed");
   for (const codeview::CVType &Rec : Records)
Index: llvm/include/llvm/ADT/ArrayRef.h
===================================================================
--- llvm/include/llvm/ADT/ArrayRef.h
+++ llvm/include/llvm/ADT/ArrayRef.h
@@ -471,6 +471,12 @@
     return Vec;
   }
 
+  /// Construct an ArrayRef from an iterator_range.
+  template <typename T>
+  ArrayRef<T> makeArrayRef(const iterator_range<const T *> &Range) {
+    return makeArrayRef(Range.begin(), Range.end());
+  }
+
   /// Construct an ArrayRef from an ArrayRef (no-op) (const)
   template <typename T> ArrayRef<T> makeArrayRef(const ArrayRef<T> &Vec) {
     return Vec;
Index: llvm/include/llvm/DebugInfo/CodeView/CVRecord.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/CVRecord.h
+++ llvm/include/llvm/DebugInfo/CodeView/CVRecord.h
@@ -14,8 +14,9 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
 #include "llvm/DebugInfo/CodeView/RecordSerialization.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cstdint>
@@ -48,15 +49,13 @@
 
 } // end namespace codeview
 
-namespace msf {
-
 template <typename Kind>
 struct VarStreamArrayExtractor<codeview::CVRecord<Kind>> {
-  Error operator()(ReadableStreamRef Stream, uint32_t &Len,
+  Error operator()(BinaryStreamRef Stream, uint32_t &Len,
                    codeview::CVRecord<Kind> &Item) const {
     using namespace codeview;
     const RecordPrefix *Prefix = nullptr;
-    StreamReader Reader(Stream);
+    BinaryStreamReader Reader(Stream, llvm::support::little);
     uint32_t Offset = Reader.getOffset();
 
     if (auto EC = Reader.readObject(Prefix))
@@ -76,8 +75,6 @@
   }
 };
 
-} // end namespace msf
-
 } // end namespace llvm
 
 #endif // LLVM_DEBUGINFO_CODEVIEW_RECORDITERATOR_H
Index: llvm/include/llvm/DebugInfo/CodeView/CVTypeVisitor.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/CVTypeVisitor.h
+++ llvm/include/llvm/DebugInfo/CodeView/CVTypeVisitor.h
@@ -34,7 +34,7 @@
   Error visitTypeStream(CVTypeRange Types);
 
   Error visitFieldListMemberStream(ArrayRef<uint8_t> FieldList);
-  Error visitFieldListMemberStream(msf::StreamReader Reader);
+  Error visitFieldListMemberStream(BinaryStreamReader Reader);
 
 private:
   /// The interface to the class that gets notified of each visitation.
Index: llvm/include/llvm/DebugInfo/CodeView/CodeViewRecordIO.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/CodeViewRecordIO.h
+++ llvm/include/llvm/DebugInfo/CodeView/CodeViewRecordIO.h
@@ -17,8 +17,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Error.h"
 #include <cassert>
 #include <cstdint>
@@ -33,8 +33,8 @@
   }
 
 public:
-  explicit CodeViewRecordIO(msf::StreamReader &Reader) : Reader(&Reader) {}
-  explicit CodeViewRecordIO(msf::StreamWriter &Writer) : Writer(&Writer) {}
+  explicit CodeViewRecordIO(BinaryStreamReader &Reader) : Reader(&Reader) {}
+  explicit CodeViewRecordIO(BinaryStreamWriter &Writer) : Writer(&Writer) {}
 
   Error beginRecord(Optional<uint32_t> MaxLength);
   Error endRecord();
@@ -59,9 +59,9 @@
 
   template <typename T> Error mapInteger(T &Value) {
     if (isWriting())
-      return Writer->writeInteger(Value, llvm::support::little);
+      return Writer->writeInteger(Value);
 
-    return Reader->readInteger(Value, llvm::support::little);
+    return Reader->readInteger(Value);
   }
 
   template <typename T> Error mapEnum(T &Value) {
@@ -93,7 +93,7 @@
     SizeType Size;
     if (isWriting()) {
       Size = static_cast<SizeType>(Items.size());
-      if (auto EC = Writer->writeInteger(Size, llvm::support::little))
+      if (auto EC = Writer->writeInteger(Size))
         return EC;
 
       for (auto &X : Items) {
@@ -101,7 +101,7 @@
           return EC;
       }
     } else {
-      if (auto EC = Reader->readInteger(Size, llvm::support::little))
+      if (auto EC = Reader->readInteger(Size))
         return EC;
       for (SizeType I = 0; I < Size; ++I) {
         typename T::value_type Item;
@@ -160,8 +160,8 @@
 
   SmallVector<RecordLimit, 2> Limits;
 
-  msf::StreamReader *Reader = nullptr;
-  msf::StreamWriter *Writer = nullptr;
+  BinaryStreamReader *Reader = nullptr;
+  BinaryStreamWriter *Writer = nullptr;
 };
 
 } // end namespace codeview
Index: llvm/include/llvm/DebugInfo/CodeView/ModuleSubstream.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/ModuleSubstream.h
+++ llvm/include/llvm/DebugInfo/CodeView/ModuleSubstream.h
@@ -11,8 +11,8 @@
 #define LLVM_DEBUGINFO_CODEVIEW_MODULESUBSTREAM_H
 
 #include "llvm/DebugInfo/CodeView/CodeView.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 
@@ -59,23 +59,22 @@
 class ModuleSubstream {
 public:
   ModuleSubstream();
-  ModuleSubstream(ModuleSubstreamKind Kind, msf::ReadableStreamRef Data);
-  static Error initialize(msf::ReadableStreamRef Stream, ModuleSubstream &Info);
+  ModuleSubstream(ModuleSubstreamKind Kind, BinaryStreamRef Data);
+  static Error initialize(BinaryStreamRef Stream, ModuleSubstream &Info);
   uint32_t getRecordLength() const;
   ModuleSubstreamKind getSubstreamKind() const;
-  msf::ReadableStreamRef getRecordData() const;
+  BinaryStreamRef getRecordData() const;
 
 private:
   ModuleSubstreamKind Kind;
-  msf::ReadableStreamRef Data;
+  BinaryStreamRef Data;
 };
 
-typedef msf::VarStreamArray<ModuleSubstream> ModuleSubstreamArray;
+typedef VarStreamArray<ModuleSubstream> ModuleSubstreamArray;
 } // namespace codeview
 
-namespace msf {
 template <> struct VarStreamArrayExtractor<codeview::ModuleSubstream> {
-  Error operator()(ReadableStreamRef Stream, uint32_t &Length,
+  Error operator()(BinaryStreamRef Stream, uint32_t &Length,
                    codeview::ModuleSubstream &Info) const {
     if (auto EC = codeview::ModuleSubstream::initialize(Stream, Info))
       return EC;
@@ -83,7 +82,6 @@
     return Error::success();
   }
 };
-} // namespace msf
 } // namespace llvm
 
 #endif // LLVM_DEBUGINFO_CODEVIEW_MODULESUBSTREAM_H
Index: llvm/include/llvm/DebugInfo/CodeView/ModuleSubstreamVisitor.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/ModuleSubstreamVisitor.h
+++ llvm/include/llvm/DebugInfo/CodeView/ModuleSubstreamVisitor.h
@@ -15,9 +15,9 @@
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
 #include "llvm/DebugInfo/CodeView/Line.h"
 #include "llvm/DebugInfo/CodeView/ModuleSubstream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cstdint>
@@ -28,8 +28,8 @@
 
 struct LineColumnEntry {
   support::ulittle32_t NameIndex;
-  msf::FixedStreamArray<LineNumberEntry> LineNumbers;
-  msf::FixedStreamArray<ColumnNumberEntry> Columns;
+  FixedStreamArray<LineNumberEntry> LineNumbers;
+  FixedStreamArray<ColumnNumberEntry> Columns;
 };
 
 struct FileChecksumEntry {
@@ -38,49 +38,47 @@
   ArrayRef<uint8_t> Checksum; // The bytes of the checksum.
 };
 
-typedef msf::VarStreamArray<LineColumnEntry> LineInfoArray;
-typedef msf::VarStreamArray<FileChecksumEntry> FileChecksumArray;
+typedef VarStreamArray<LineColumnEntry> LineInfoArray;
+typedef VarStreamArray<FileChecksumEntry> FileChecksumArray;
 
 class IModuleSubstreamVisitor {
 public:
   virtual ~IModuleSubstreamVisitor() = default;
 
   virtual Error visitUnknown(ModuleSubstreamKind Kind,
-                             msf::ReadableStreamRef Data) = 0;
-  virtual Error visitSymbols(msf::ReadableStreamRef Data);
-  virtual Error visitLines(msf::ReadableStreamRef Data,
+                             BinaryStreamRef Data) = 0;
+  virtual Error visitSymbols(BinaryStreamRef Data);
+  virtual Error visitLines(BinaryStreamRef Data,
                            const LineSubstreamHeader *Header,
                            const LineInfoArray &Lines);
-  virtual Error visitStringTable(msf::ReadableStreamRef Data);
-  virtual Error visitFileChecksums(msf::ReadableStreamRef Data,
+  virtual Error visitStringTable(BinaryStreamRef Data);
+  virtual Error visitFileChecksums(BinaryStreamRef Data,
                                    const FileChecksumArray &Checksums);
-  virtual Error visitFrameData(msf::ReadableStreamRef Data);
-  virtual Error visitInlineeLines(msf::ReadableStreamRef Data);
-  virtual Error visitCrossScopeImports(msf::ReadableStreamRef Data);
-  virtual Error visitCrossScopeExports(msf::ReadableStreamRef Data);
-  virtual Error visitILLines(msf::ReadableStreamRef Data);
-  virtual Error visitFuncMDTokenMap(msf::ReadableStreamRef Data);
-  virtual Error visitTypeMDTokenMap(msf::ReadableStreamRef Data);
-  virtual Error visitMergedAssemblyInput(msf::ReadableStreamRef Data);
-  virtual Error visitCoffSymbolRVA(msf::ReadableStreamRef Data);
+  virtual Error visitFrameData(BinaryStreamRef Data);
+  virtual Error visitInlineeLines(BinaryStreamRef Data);
+  virtual Error visitCrossScopeImports(BinaryStreamRef Data);
+  virtual Error visitCrossScopeExports(BinaryStreamRef Data);
+  virtual Error visitILLines(BinaryStreamRef Data);
+  virtual Error visitFuncMDTokenMap(BinaryStreamRef Data);
+  virtual Error visitTypeMDTokenMap(BinaryStreamRef Data);
+  virtual Error visitMergedAssemblyInput(BinaryStreamRef Data);
+  virtual Error visitCoffSymbolRVA(BinaryStreamRef Data);
 };
 
 Error visitModuleSubstream(const ModuleSubstream &R,
                            IModuleSubstreamVisitor &V);
 } // end namespace codeview
 
-namespace msf {
-
 template <> class VarStreamArrayExtractor<codeview::LineColumnEntry> {
 public:
   VarStreamArrayExtractor(const codeview::LineSubstreamHeader *Header)
       : Header(Header) {}
 
-  Error operator()(ReadableStreamRef Stream, uint32_t &Len,
+  Error operator()(BinaryStreamRef Stream, uint32_t &Len,
                    codeview::LineColumnEntry &Item) const {
     using namespace codeview;
     const LineFileBlockHeader *BlockHeader;
-    StreamReader Reader(Stream);
+    BinaryStreamReader Reader(Stream, llvm::support::little);
     if (auto EC = Reader.readObject(BlockHeader))
       return EC;
     bool HasColumn = Header->Flags & LineFlags::HaveColumns;
@@ -113,11 +111,11 @@
 
 template <> class VarStreamArrayExtractor<codeview::FileChecksumEntry> {
 public:
-  Error operator()(ReadableStreamRef Stream, uint32_t &Len,
+  Error operator()(BinaryStreamRef Stream, uint32_t &Len,
                    codeview::FileChecksumEntry &Item) const {
     using namespace codeview;
     const FileChecksum *Header;
-    StreamReader Reader(Stream);
+    BinaryStreamReader Reader(Stream, llvm::support::little);
     if (auto EC = Reader.readObject(Header))
       return EC;
     Item.FileNameOffset = Header->FileNameOffset;
@@ -129,8 +127,6 @@
   }
 };
 
-} // end namespace msf
-
 } // end namespace llvm
 
 #endif // LLVM_DEBUGINFO_CODEVIEW_MODULESUBSTREAMVISITOR_H
Index: llvm/include/llvm/DebugInfo/CodeView/RecordSerialization.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/RecordSerialization.h
+++ llvm/include/llvm/DebugInfo/CodeView/RecordSerialization.h
@@ -15,7 +15,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/DebugInfo/CodeView/CodeView.h"
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cinttypes>
@@ -41,37 +41,37 @@
 StringRef getBytesAsCharacters(ArrayRef<uint8_t> LeafData);
 StringRef getBytesAsCString(ArrayRef<uint8_t> LeafData);
 
-inline Error consume(msf::StreamReader &Reader) { return Error::success(); }
+inline Error consume(BinaryStreamReader &Reader) { return Error::success(); }
 
 /// Decodes a numeric "leaf" value. These are integer literals encountered in
 /// the type stream. If the value is positive and less than LF_NUMERIC (1 <<
 /// 15), it is emitted directly in Data. Otherwise, it has a tag like LF_CHAR
 /// that indicates the bitwidth and sign of the numeric data.
-Error consume(msf::StreamReader &Reader, APSInt &Num);
+Error consume(BinaryStreamReader &Reader, APSInt &Num);
 
 /// Decodes a numeric leaf value that is known to be a particular type.
-Error consume_numeric(msf::StreamReader &Reader, uint64_t &Value);
+Error consume_numeric(BinaryStreamReader &Reader, uint64_t &Value);
 
 /// Decodes signed and unsigned fixed-length integers.
-Error consume(msf::StreamReader &Reader, uint32_t &Item);
-Error consume(msf::StreamReader &Reader, int32_t &Item);
+Error consume(BinaryStreamReader &Reader, uint32_t &Item);
+Error consume(BinaryStreamReader &Reader, int32_t &Item);
 
 /// Decodes a null terminated string.
-Error consume(msf::StreamReader &Reader, StringRef &Item);
+Error consume(BinaryStreamReader &Reader, StringRef &Item);
 
 Error consume(StringRef &Data, APSInt &Num);
 Error consume(StringRef &Data, uint32_t &Item);
 
 /// Decodes an arbitrary object whose layout matches that of the underlying
 /// byte sequence, and returns a pointer to the object.
-template <typename T> Error consume(msf::StreamReader &Reader, T *&Item) {
+template <typename T> Error consume(BinaryStreamReader &Reader, T *&Item) {
   return Reader.readObject(Item);
 }
 
 template <typename T, typename U> struct serialize_conditional_impl {
   serialize_conditional_impl(T &Item, U Func) : Item(Item), Func(Func) {}
 
-  Error deserialize(msf::StreamReader &Reader) const {
+  Error deserialize(BinaryStreamReader &Reader) const {
     if (!Func())
       return Error::success();
     return consume(Reader, Item);
@@ -89,7 +89,7 @@
 template <typename T, typename U> struct serialize_array_impl {
   serialize_array_impl(ArrayRef<T> &Item, U Func) : Item(Item), Func(Func) {}
 
-  Error deserialize(msf::StreamReader &Reader) const {
+  Error deserialize(BinaryStreamReader &Reader) const {
     return Reader.readArray(Item, Func());
   }
 
@@ -100,7 +100,7 @@
 template <typename T> struct serialize_vector_tail_impl {
   serialize_vector_tail_impl(std::vector<T> &Item) : Item(Item) {}
 
-  Error deserialize(msf::StreamReader &Reader) const {
+  Error deserialize(BinaryStreamReader &Reader) const {
     T Field;
     // Stop when we run out of bytes or we hit record padding bytes.
     while (!Reader.empty() && Reader.peek() < LF_PAD0) {
@@ -118,7 +118,7 @@
   serialize_null_term_string_array_impl(std::vector<StringRef> &Item)
       : Item(Item) {}
 
-  Error deserialize(msf::StreamReader &Reader) const {
+  Error deserialize(BinaryStreamReader &Reader) const {
     if (Reader.empty())
       return make_error<CodeViewError>(cv_error_code::insufficient_buffer,
                                        "Null terminated string is empty!");
@@ -138,7 +138,7 @@
 template <typename T> struct serialize_arrayref_tail_impl {
   serialize_arrayref_tail_impl(ArrayRef<T> &Item) : Item(Item) {}
 
-  Error deserialize(msf::StreamReader &Reader) const {
+  Error deserialize(BinaryStreamReader &Reader) const {
     uint32_t Count = Reader.bytesRemaining() / sizeof(T);
     return Reader.readArray(Item, Count);
   }
@@ -149,7 +149,7 @@
 template <typename T> struct serialize_numeric_impl {
   serialize_numeric_impl(T &Item) : Item(Item) {}
 
-  Error deserialize(msf::StreamReader &Reader) const {
+  Error deserialize(BinaryStreamReader &Reader) const {
     return consume_numeric(Reader, Item);
   }
 
@@ -201,42 +201,42 @@
 #define CV_NUMERIC_FIELD(I) serialize_numeric(I)
 
 template <typename T, typename U>
-Error consume(msf::StreamReader &Reader,
+Error consume(BinaryStreamReader &Reader,
               const serialize_conditional_impl<T, U> &Item) {
   return Item.deserialize(Reader);
 }
 
 template <typename T, typename U>
-Error consume(msf::StreamReader &Reader,
+Error consume(BinaryStreamReader &Reader,
               const serialize_array_impl<T, U> &Item) {
   return Item.deserialize(Reader);
 }
 
-inline Error consume(msf::StreamReader &Reader,
+inline Error consume(BinaryStreamReader &Reader,
                      const serialize_null_term_string_array_impl &Item) {
   return Item.deserialize(Reader);
 }
 
 template <typename T>
-Error consume(msf::StreamReader &Reader,
+Error consume(BinaryStreamReader &Reader,
               const serialize_vector_tail_impl<T> &Item) {
   return Item.deserialize(Reader);
 }
 
 template <typename T>
-Error consume(msf::StreamReader &Reader,
+Error consume(BinaryStreamReader &Reader,
               const serialize_arrayref_tail_impl<T> &Item) {
   return Item.deserialize(Reader);
 }
 
 template <typename T>
-Error consume(msf::StreamReader &Reader,
+Error consume(BinaryStreamReader &Reader,
               const serialize_numeric_impl<T> &Item) {
   return Item.deserialize(Reader);
 }
 
 template <typename T, typename U, typename... Args>
-Error consume(msf::StreamReader &Reader, T &&X, U &&Y, Args &&... Rest) {
+Error consume(BinaryStreamReader &Reader, T &&X, U &&Y, Args &&... Rest) {
   if (auto EC = consume(Reader, X))
     return EC;
   return consume(Reader, Y, std::forward<Args>(Rest)...);
Index: llvm/include/llvm/DebugInfo/CodeView/SymbolDeserializer.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/SymbolDeserializer.h
+++ llvm/include/llvm/DebugInfo/CodeView/SymbolDeserializer.h
@@ -15,8 +15,8 @@
 #include "llvm/DebugInfo/CodeView/SymbolRecordMapping.h"
 #include "llvm/DebugInfo/CodeView/SymbolVisitorCallbacks.h"
 #include "llvm/DebugInfo/CodeView/SymbolVisitorDelegate.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
@@ -25,10 +25,11 @@
 class SymbolDeserializer : public SymbolVisitorCallbacks {
   struct MappingInfo {
     explicit MappingInfo(ArrayRef<uint8_t> RecordData)
-        : Stream(RecordData), Reader(Stream), Mapping(Reader) {}
+        : Stream(RecordData), Reader(Stream, llvm::support::little),
+          Mapping(Reader) {}
 
-    msf::ByteStream Stream;
-    msf::StreamReader Reader;
+    BinaryByteStream Stream;
+    BinaryStreamReader Reader;
     SymbolRecordMapping Mapping;
   };
 
Index: llvm/include/llvm/DebugInfo/CodeView/SymbolRecord.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/SymbolRecord.h
+++ llvm/include/llvm/DebugInfo/CodeView/SymbolRecord.h
@@ -13,13 +13,13 @@
 #include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
-#include "llvm/ADT/iterator_range.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator_range.h"
 #include "llvm/DebugInfo/CodeView/CVRecord.h"
 #include "llvm/DebugInfo/CodeView/CodeView.h"
 #include "llvm/DebugInfo/CodeView/RecordSerialization.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cstddef>
@@ -938,7 +938,7 @@
 };
 
 typedef CVRecord<SymbolKind> CVSymbol;
-typedef msf::VarStreamArray<CVSymbol> CVSymbolArray;
+typedef VarStreamArray<CVSymbol> CVSymbolArray;
 
 } // end namespace codeview
 } // end namespace llvm
Index: llvm/include/llvm/DebugInfo/CodeView/SymbolRecordMapping.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/SymbolRecordMapping.h
+++ llvm/include/llvm/DebugInfo/CodeView/SymbolRecordMapping.h
@@ -14,16 +14,14 @@
 #include "llvm/DebugInfo/CodeView/SymbolVisitorCallbacks.h"
 
 namespace llvm {
-namespace msf {
-class StreamReader;
-class StreamWriter;
-}
+class BinaryStreamReader;
+class BinaryStreamWriter;
 
 namespace codeview {
 class SymbolRecordMapping : public SymbolVisitorCallbacks {
 public:
-  explicit SymbolRecordMapping(msf::StreamReader &Reader) : IO(Reader) {}
-  explicit SymbolRecordMapping(msf::StreamWriter &Writer) : IO(Writer) {}
+  explicit SymbolRecordMapping(BinaryStreamReader &Reader) : IO(Reader) {}
+  explicit SymbolRecordMapping(BinaryStreamWriter &Writer) : IO(Writer) {}
 
   Error visitSymbolBegin(CVSymbol &Record) override;
   Error visitSymbolEnd(CVSymbol &Record) override;
Index: llvm/include/llvm/DebugInfo/CodeView/SymbolSerializer.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/SymbolSerializer.h
+++ llvm/include/llvm/DebugInfo/CodeView/SymbolSerializer.h
@@ -12,8 +12,6 @@
 
 #include "llvm/DebugInfo/CodeView/SymbolRecordMapping.h"
 #include "llvm/DebugInfo/CodeView/SymbolVisitorCallbacks.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
@@ -21,6 +19,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
@@ -28,7 +28,7 @@
 
 class SymbolSerializer : public SymbolVisitorCallbacks {
   uint32_t RecordStart = 0;
-  msf::StreamWriter &Writer;
+  BinaryStreamWriter &Writer;
   SymbolRecordMapping Mapping;
   Optional<SymbolKind> CurrentSymbol;
 
@@ -42,7 +42,7 @@
   }
 
 public:
-  explicit SymbolSerializer(msf::StreamWriter &Writer)
+  explicit SymbolSerializer(BinaryStreamWriter &Writer)
       : Writer(Writer), Mapping(Writer) {}
 
   virtual Error visitSymbolBegin(CVSymbol &Record) override {
Index: llvm/include/llvm/DebugInfo/CodeView/SymbolVisitorDelegate.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/SymbolVisitorDelegate.h
+++ llvm/include/llvm/DebugInfo/CodeView/SymbolVisitorDelegate.h
@@ -15,9 +15,7 @@
 
 namespace llvm {
 
-namespace msf {
-class StreamReader;
-} // end namespace msf
+class BinaryStreamReader;
 
 namespace codeview {
 
@@ -25,7 +23,7 @@
 public:
   virtual ~SymbolVisitorDelegate() = default;
 
-  virtual uint32_t getRecordOffset(msf::StreamReader Reader) = 0;
+  virtual uint32_t getRecordOffset(BinaryStreamReader Reader) = 0;
   virtual StringRef getFileNameForFileOffset(uint32_t FileOffset) = 0;
   virtual StringRef getStringTable() = 0;
 };
Index: llvm/include/llvm/DebugInfo/CodeView/TypeDeserializer.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/TypeDeserializer.h
+++ llvm/include/llvm/DebugInfo/CodeView/TypeDeserializer.h
@@ -16,8 +16,8 @@
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeRecordMapping.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Error.h"
 #include <cassert>
 #include <cstdint>
@@ -29,10 +29,11 @@
 class TypeDeserializer : public TypeVisitorCallbacks {
   struct MappingInfo {
     explicit MappingInfo(ArrayRef<uint8_t> RecordData)
-        : Stream(RecordData), Reader(Stream), Mapping(Reader) {}
+        : Stream(RecordData), Reader(Stream, llvm::support::little),
+          Mapping(Reader) {}
 
-    msf::ByteStream Stream;
-    msf::StreamReader Reader;
+    BinaryByteStream Stream;
+    BinaryStreamReader Reader;
     TypeRecordMapping Mapping;
   };
 
@@ -72,16 +73,16 @@
 
 class FieldListDeserializer : public TypeVisitorCallbacks {
   struct MappingInfo {
-    explicit MappingInfo(msf::StreamReader &R)
+    explicit MappingInfo(BinaryStreamReader &R)
         : Reader(R), Mapping(Reader), StartOffset(0) {}
 
-    msf::StreamReader &Reader;
+    BinaryStreamReader &Reader;
     TypeRecordMapping Mapping;
     uint32_t StartOffset;
   };
 
 public:
-  explicit FieldListDeserializer(msf::StreamReader &Reader) : Mapping(Reader) {
+  explicit FieldListDeserializer(BinaryStreamReader &Reader) : Mapping(Reader) {
     CVType FieldList;
     FieldList.Type = TypeLeafKind::LF_FIELDLIST;
     consumeError(Mapping.Mapping.visitTypeBegin(FieldList));
Index: llvm/include/llvm/DebugInfo/CodeView/TypeRecord.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/TypeRecord.h
+++ llvm/include/llvm/DebugInfo/CodeView/TypeRecord.h
@@ -18,7 +18,7 @@
 #include "llvm/DebugInfo/CodeView/CVRecord.h"
 #include "llvm/DebugInfo/CodeView/CodeView.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/Endian.h"
 #include <algorithm>
 #include <cstdint>
@@ -26,9 +26,7 @@
 
 namespace llvm {
 
-namespace msf {
-class StreamReader;
-} // end namespace msf
+class BinaryStreamReader;
 
 namespace codeview {
 
@@ -42,7 +40,7 @@
   TypeLeafKind Kind;
   ArrayRef<uint8_t> Data;
 };
-typedef msf::VarStreamArray<CVType> CVTypeArray;
+typedef VarStreamArray<CVType> CVTypeArray;
 typedef iterator_range<CVTypeArray::Iterator> CVTypeRange;
 
 /// Equvalent to CV_fldattr_t in cvinfo.h.
Index: llvm/include/llvm/DebugInfo/CodeView/TypeRecordMapping.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/TypeRecordMapping.h
+++ llvm/include/llvm/DebugInfo/CodeView/TypeRecordMapping.h
@@ -16,15 +16,14 @@
 #include "llvm/Support/Error.h"
 
 namespace llvm {
-namespace msf {
-class StreamReader;
-class StreamWriter;
-}
+class BinaryStreamReader;
+class BinaryStreamWriter;
+
 namespace codeview {
 class TypeRecordMapping : public TypeVisitorCallbacks {
 public:
-  explicit TypeRecordMapping(msf::StreamReader &Reader) : IO(Reader) {}
-  explicit TypeRecordMapping(msf::StreamWriter &Writer) : IO(Writer) {}
+  explicit TypeRecordMapping(BinaryStreamReader &Reader) : IO(Reader) {}
+  explicit TypeRecordMapping(BinaryStreamWriter &Writer) : IO(Writer) {}
 
   Error visitTypeBegin(CVType &Record) override;
   Error visitTypeEnd(CVType &Record) override;
Index: llvm/include/llvm/DebugInfo/CodeView/TypeSerializer.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/TypeSerializer.h
+++ llvm/include/llvm/DebugInfo/CodeView/TypeSerializer.h
@@ -12,14 +12,14 @@
 
 #include "llvm/DebugInfo/CodeView/TypeRecordMapping.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
@@ -56,8 +56,8 @@
   Optional<TypeLeafKind> TypeKind;
   Optional<TypeLeafKind> MemberKind;
   std::vector<uint8_t> RecordBuffer;
-  msf::MutableByteStream Stream;
-  msf::StreamWriter Writer;
+  MutableBinaryByteStream Stream;
+  BinaryStreamWriter Writer;
   TypeRecordMapping Mapping;
 
   RecordList SeenRecords;
@@ -109,7 +109,7 @@
   Error visitKnownMemberImpl(CVMemberRecord &CVR, RecordType &Record) {
     assert(CVR.Kind == static_cast<TypeLeafKind>(Record.getKind()));
 
-    if (auto EC = Writer.writeEnum(CVR.Kind, llvm::support::little))
+    if (auto EC = Writer.writeEnum(CVR.Kind))
       return EC;
 
     if (auto EC = Mapping.visitKnownMember(CVR, Record))
Index: llvm/include/llvm/DebugInfo/MSF/ByteStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/ByteStream.h
+++ /dev/null
@@ -1,169 +0,0 @@
-//===- ByteStream.h - Reads stream data from a byte sequence ----*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_DEBUGINFO_MSF_BYTESTREAM_H
-#define LLVM_DEBUGINFO_MSF_BYTESTREAM_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/DebugInfo/MSF/MSFError.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
-#include "llvm/Support/Error.h"
-#include "llvm/Support/FileOutputBuffer.h"
-#include "llvm/Support/MemoryBuffer.h"
-#include <algorithm>
-#include <cstdint>
-#include <cstring>
-#include <memory>
-
-namespace llvm {
-namespace msf {
-
-class ByteStream : public ReadableStream {
-public:
-  ByteStream() = default;
-  explicit ByteStream(ArrayRef<uint8_t> Data) : Data(Data) {}
-  explicit ByteStream(StringRef Data)
-      : Data(Data.bytes_begin(), Data.bytes_end()) {}
-
-  Error readBytes(uint32_t Offset, uint32_t Size,
-                  ArrayRef<uint8_t> &Buffer) const override {
-    if (Offset > Data.size())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    if (Data.size() < Size + Offset)
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    Buffer = Data.slice(Offset, Size);
-    return Error::success();
-  }
-
-  Error readLongestContiguousChunk(uint32_t Offset,
-                                   ArrayRef<uint8_t> &Buffer) const override {
-    if (Offset >= Data.size())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    Buffer = Data.slice(Offset);
-    return Error::success();
-  }
-
-  uint32_t getLength() const override { return Data.size(); }
-
-  ArrayRef<uint8_t> data() const { return Data; }
-
-  StringRef str() const {
-    const char *CharData = reinterpret_cast<const char *>(Data.data());
-    return StringRef(CharData, Data.size());
-  }
-
-protected:
-  ArrayRef<uint8_t> Data;
-};
-
-// MemoryBufferByteStream behaves like a read-only ByteStream, but has its data
-// backed by an llvm::MemoryBuffer.  It also owns the underlying MemoryBuffer.
-class MemoryBufferByteStream : public ByteStream {
-public:
-  explicit MemoryBufferByteStream(std::unique_ptr<MemoryBuffer> Buffer)
-      : ByteStream(ArrayRef<uint8_t>(Buffer->getBuffer().bytes_begin(),
-                                     Buffer->getBuffer().bytes_end())),
-        MemBuffer(std::move(Buffer)) {}
-
-  std::unique_ptr<MemoryBuffer> MemBuffer;
-};
-
-class MutableByteStream : public WritableStream {
-public:
-  MutableByteStream() = default;
-  explicit MutableByteStream(MutableArrayRef<uint8_t> Data)
-      : Data(Data), ImmutableStream(Data) {}
-
-  Error readBytes(uint32_t Offset, uint32_t Size,
-                  ArrayRef<uint8_t> &Buffer) const override {
-    return ImmutableStream.readBytes(Offset, Size, Buffer);
-  }
-
-  Error readLongestContiguousChunk(uint32_t Offset,
-                                   ArrayRef<uint8_t> &Buffer) const override {
-    return ImmutableStream.readLongestContiguousChunk(Offset, Buffer);
-  }
-
-  uint32_t getLength() const override { return ImmutableStream.getLength(); }
-
-  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Buffer) const override {
-    if (Buffer.empty())
-      return Error::success();
-
-    if (Data.size() < Buffer.size())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    if (Offset > Buffer.size() - Data.size())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-
-    uint8_t *DataPtr = const_cast<uint8_t *>(Data.data());
-    ::memcpy(DataPtr + Offset, Buffer.data(), Buffer.size());
-    return Error::success();
-  }
-
-  Error commit() const override { return Error::success(); }
-
-  MutableArrayRef<uint8_t> data() const { return Data; }
-
-private:
-  MutableArrayRef<uint8_t> Data;
-  ByteStream ImmutableStream;
-};
-
-// A simple adapter that acts like a ByteStream but holds ownership over
-// and underlying FileOutputBuffer.
-class FileBufferByteStream : public WritableStream {
-private:
-  class StreamImpl : public MutableByteStream {
-  public:
-    StreamImpl(std::unique_ptr<FileOutputBuffer> Buffer)
-        : MutableByteStream(MutableArrayRef<uint8_t>(Buffer->getBufferStart(),
-                                                     Buffer->getBufferEnd())),
-          FileBuffer(std::move(Buffer)) {}
-
-    Error commit() const override {
-      if (FileBuffer->commit())
-        return llvm::make_error<MSFError>(msf_error_code::not_writable);
-      return Error::success();
-    }
-
-  private:
-    std::unique_ptr<FileOutputBuffer> FileBuffer;
-  };
-
-public:
-  explicit FileBufferByteStream(std::unique_ptr<FileOutputBuffer> Buffer)
-      : Impl(std::move(Buffer)) {}
-
-  Error readBytes(uint32_t Offset, uint32_t Size,
-                  ArrayRef<uint8_t> &Buffer) const override {
-    return Impl.readBytes(Offset, Size, Buffer);
-  }
-
-  Error readLongestContiguousChunk(uint32_t Offset,
-                                   ArrayRef<uint8_t> &Buffer) const override {
-    return Impl.readLongestContiguousChunk(Offset, Buffer);
-  }
-
-  uint32_t getLength() const override { return Impl.getLength(); }
-
-  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) const override {
-    return Impl.writeBytes(Offset, Data);
-  }
-
-  Error commit() const override { return Impl.commit(); }
-
-private:
-  StreamImpl Impl;
-};
-
-} // end namespace msf
-} // end namespace llvm
-
-#endif // LLVM_DEBUGINFO_MSF_BYTESTREAM_H
Index: llvm/include/llvm/DebugInfo/MSF/MappedBlockStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/MappedBlockStream.h
+++ llvm/include/llvm/DebugInfo/MSF/MappedBlockStream.h
@@ -15,8 +15,9 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/DebugInfo/MSF/MSFStreamLayout.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cstdint>
@@ -37,29 +38,29 @@
 /// the MSF.  MappedBlockStream provides methods for reading from and writing
 /// to one of these streams transparently, as if it were a contiguous sequence
 /// of bytes.
-class MappedBlockStream : public ReadableStream {
+class MappedBlockStream : public BinaryStream {
   friend class WritableMappedBlockStream;
 public:
   static std::unique_ptr<MappedBlockStream>
   createStream(uint32_t BlockSize, uint32_t NumBlocks,
-               const MSFStreamLayout &Layout, const ReadableStream &MsfData);
+               const MSFStreamLayout &Layout, BinaryStreamRef MsfData);
 
   static std::unique_ptr<MappedBlockStream>
-  createIndexedStream(const MSFLayout &Layout, const ReadableStream &MsfData,
+  createIndexedStream(const MSFLayout &Layout, BinaryStreamRef MsfData,
                       uint32_t StreamIndex);
 
   static std::unique_ptr<MappedBlockStream>
-  createFpmStream(const MSFLayout &Layout, const ReadableStream &MsfData);
+  createFpmStream(const MSFLayout &Layout, BinaryStreamRef MsfData);
 
   static std::unique_ptr<MappedBlockStream>
-  createDirectoryStream(const MSFLayout &Layout, const ReadableStream &MsfData);
+  createDirectoryStream(const MSFLayout &Layout, BinaryStreamRef MsfData);
 
   Error readBytes(uint32_t Offset, uint32_t Size,
-                  ArrayRef<uint8_t> &Buffer) const override;
+                  ArrayRef<uint8_t> &Buffer) override;
   Error readLongestContiguousChunk(uint32_t Offset,
-                                   ArrayRef<uint8_t> &Buffer) const override;
+                                   ArrayRef<uint8_t> &Buffer) override;
 
-  uint32_t getLength() const override;
+  uint32_t getLength() override;
 
   uint32_t getNumBytesCopied() const;
 
@@ -74,51 +75,52 @@
 protected:
   MappedBlockStream(uint32_t BlockSize, uint32_t NumBlocks,
                     const MSFStreamLayout &StreamLayout,
-                    const ReadableStream &MsfData);
+                    BinaryStreamRef MsfData);
 
 private:
   const MSFStreamLayout &getStreamLayout() const { return StreamLayout; }
   void fixCacheAfterWrite(uint32_t Offset, ArrayRef<uint8_t> Data) const;
 
-  Error readBytes(uint32_t Offset, MutableArrayRef<uint8_t> Buffer) const;
+  Error readBytes(uint32_t Offset, MutableArrayRef<uint8_t> Buffer);
   bool tryReadContiguously(uint32_t Offset, uint32_t Size,
-                           ArrayRef<uint8_t> &Buffer) const;
+                           ArrayRef<uint8_t> &Buffer);
 
   const uint32_t BlockSize;
   const uint32_t NumBlocks;
   const MSFStreamLayout StreamLayout;
-  const ReadableStream &MsfData;
+  BinaryStreamRef MsfData;
 
   typedef MutableArrayRef<uint8_t> CacheEntry;
   mutable llvm::BumpPtrAllocator Pool;
   mutable DenseMap<uint32_t, std::vector<CacheEntry>> CacheMap;
 };
 
-class WritableMappedBlockStream : public WritableStream {
+class WritableMappedBlockStream : public WritableBinaryStream {
 public:
   static std::unique_ptr<WritableMappedBlockStream>
   createStream(uint32_t BlockSize, uint32_t NumBlocks,
-               const MSFStreamLayout &Layout, const WritableStream &MsfData);
+               const MSFStreamLayout &Layout, WritableBinaryStreamRef MsfData);
 
   static std::unique_ptr<WritableMappedBlockStream>
-  createIndexedStream(const MSFLayout &Layout, const WritableStream &MsfData,
+  createIndexedStream(const MSFLayout &Layout, WritableBinaryStreamRef MsfData,
                       uint32_t StreamIndex);
 
   static std::unique_ptr<WritableMappedBlockStream>
-  createDirectoryStream(const MSFLayout &Layout, const WritableStream &MsfData);
+  createDirectoryStream(const MSFLayout &Layout,
+                        WritableBinaryStreamRef MsfData);
 
   static std::unique_ptr<WritableMappedBlockStream>
-  createFpmStream(const MSFLayout &Layout, const WritableStream &MsfData);
+  createFpmStream(const MSFLayout &Layout, WritableBinaryStreamRef MsfData);
 
   Error readBytes(uint32_t Offset, uint32_t Size,
-                  ArrayRef<uint8_t> &Buffer) const override;
+                  ArrayRef<uint8_t> &Buffer) override;
   Error readLongestContiguousChunk(uint32_t Offset,
-                                   ArrayRef<uint8_t> &Buffer) const override;
-  uint32_t getLength() const override;
+                                   ArrayRef<uint8_t> &Buffer) override;
+  uint32_t getLength() override;
 
-  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Buffer) const override;
+  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Buffer) override;
 
-  Error commit() const override;
+  Error commit() override;
 
   const MSFStreamLayout &getStreamLayout() const {
     return ReadInterface.getStreamLayout();
@@ -130,12 +132,12 @@
 protected:
   WritableMappedBlockStream(uint32_t BlockSize, uint32_t NumBlocks,
                             const MSFStreamLayout &StreamLayout,
-                            const WritableStream &MsfData);
+                            WritableBinaryStreamRef MsfData);
 
 private:
   MappedBlockStream ReadInterface;
 
-  const WritableStream &WriteInterface;
+  WritableBinaryStreamRef WriteInterface;
 };
 
 } // end namespace pdb
Index: llvm/include/llvm/DebugInfo/MSF/SequencedItemStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/SequencedItemStream.h
+++ /dev/null
@@ -1,93 +0,0 @@
-//===- SequencedItemStream.h ------------------------------------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_DEBUGINFO_MSF_SEQUENCEDITEMSTREAM_H
-#define LLVM_DEBUGINFO_MSF_SEQUENCEDITEMSTREAM_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/DebugInfo/MSF/MSFError.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
-#include "llvm/Support/Error.h"
-#include <cstddef>
-#include <cstdint>
-
-namespace llvm {
-namespace msf {
-
-template <typename T> struct SequencedItemTraits {
-  static size_t length(const T &Item) = delete;
-  static ArrayRef<uint8_t> bytes(const T &Item) = delete;
-};
-
-/// SequencedItemStream represents a sequence of objects stored in a
-/// standard container but for which it is useful to view as a stream of
-/// contiguous bytes.  An example of this might be if you have a std::vector
-/// of TPI records, where each record contains a byte sequence that
-/// represents that one record serialized, but where each consecutive item
-/// might not be allocated immediately after the previous item.  Using a
-/// SequencedItemStream, we can adapt the VarStreamArray class to trivially
-/// extract one item at a time, allowing the data to be used anywhere a
-/// VarStreamArray could be used.
-template <typename T, typename Traits = SequencedItemTraits<T>>
-class SequencedItemStream : public ReadableStream {
-public:
-  SequencedItemStream() = default;
-
-  Error readBytes(uint32_t Offset, uint32_t Size,
-                  ArrayRef<uint8_t> &Buffer) const override {
-    auto ExpectedIndex = translateOffsetIndex(Offset);
-    if (!ExpectedIndex)
-      return ExpectedIndex.takeError();
-    const auto &Item = Items[*ExpectedIndex];
-    if (Size > Traits::length(Item))
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    Buffer = Traits::bytes(Item).take_front(Size);
-    return Error::success();
-  }
-
-  Error readLongestContiguousChunk(uint32_t Offset,
-                                   ArrayRef<uint8_t> &Buffer) const override {
-    auto ExpectedIndex = translateOffsetIndex(Offset);
-    if (!ExpectedIndex)
-      return ExpectedIndex.takeError();
-    Buffer = Traits::bytes(Items[*ExpectedIndex]);
-    return Error::success();
-  }
-
-  void setItems(ArrayRef<T> ItemArray) { Items = ItemArray; }
-
-  uint32_t getLength() const override {
-    uint32_t Size = 0;
-    for (const auto &Item : Items)
-      Size += Traits::length(Item);
-    return Size;
-  }
-
-private:
-  Expected<uint32_t> translateOffsetIndex(uint32_t Offset) const {
-    uint32_t CurrentOffset = 0;
-    uint32_t CurrentIndex = 0;
-    for (const auto &Item : Items) {
-      if (CurrentOffset >= Offset)
-        break;
-      CurrentOffset += Traits::length(Item);
-      ++CurrentIndex;
-    }
-    if (CurrentOffset != Offset)
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    return CurrentIndex;
-  }
-
-  ArrayRef<T> Items;
-};
-
-} // end namespace msf
-} // end namespace llvm
-
-#endif // LLVM_DEBUGINFO_MSF_SEQUENCEDITEMSTREAM_H
Index: llvm/include/llvm/DebugInfo/MSF/StreamArray.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/StreamArray.h
+++ /dev/null
@@ -1,304 +0,0 @@
-//===- StreamArray.h - Array backed by an arbitrary stream ------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_DEBUGINFO_MSF_STREAMARRAY_H
-#define LLVM_DEBUGINFO_MSF_STREAMARRAY_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/iterator.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
-#include "llvm/Support/Error.h"
-#include <cassert>
-#include <cstdint>
-
-namespace llvm {
-namespace msf {
-
-/// VarStreamArrayExtractor is intended to be specialized to provide customized
-/// extraction logic.  On input it receives a StreamRef pointing to the
-/// beginning of the next record, but where the length of the record is not yet
-/// known.  Upon completion, it should return an appropriate Error instance if
-/// a record could not be extracted, or if one could be extracted it should
-/// return success and set Len to the number of bytes this record occupied in
-/// the underlying stream, and it should fill out the fields of the value type
-/// Item appropriately to represent the current record.
-///
-/// You can specialize this template for your own custom value types to avoid
-/// having to specify a second template argument to VarStreamArray (documented
-/// below).
-template <typename T> struct VarStreamArrayExtractor {
-  // Method intentionally deleted.  You must provide an explicit specialization
-  // with the following method implemented.
-  Error operator()(ReadableStreamRef Stream, uint32_t &Len,
-                   T &Item) const = delete;
-};
-
-/// VarStreamArray represents an array of variable length records backed by a
-/// stream.  This could be a contiguous sequence of bytes in memory, it could
-/// be a file on disk, or it could be a PDB stream where bytes are stored as
-/// discontiguous blocks in a file.  Usually it is desirable to treat arrays
-/// as contiguous blocks of memory, but doing so with large PDB files, for
-/// example, could mean allocating huge amounts of memory just to allow
-/// re-ordering of stream data to be contiguous before iterating over it.  By
-/// abstracting this out, we need not duplicate this memory, and we can
-/// iterate over arrays in arbitrarily formatted streams.  Elements are parsed
-/// lazily on iteration, so there is no upfront cost associated with building
-/// a VarStreamArray, no matter how large it may be.
-///
-/// You create a VarStreamArray by specifying a ValueType and an Extractor type.
-/// If you do not specify an Extractor type, it expects you to specialize
-/// VarStreamArrayExtractor<T> for your ValueType.
-///
-/// By default an Extractor is default constructed in the class, but in some
-/// cases you might find it useful for an Extractor to maintain state across
-/// extractions.  In this case you can provide your own Extractor through a
-/// secondary constructor.  The following examples show various ways of
-/// creating a VarStreamArray.
-///
-///       // Will use VarStreamArrayExtractor<MyType> as the extractor.
-///       VarStreamArray<MyType> MyTypeArray;
-///
-///       // Will use a default-constructed MyExtractor as the extractor.
-///       VarStreamArray<MyType, MyExtractor> MyTypeArray2;
-///
-///       // Will use the specific instance of MyExtractor provided.
-///       // MyExtractor need not be default-constructible in this case.
-///       MyExtractor E(SomeContext);
-///       VarStreamArray<MyType, MyExtractor> MyTypeArray3(E);
-///
-template <typename ValueType, typename Extractor> class VarStreamArrayIterator;
-
-template <typename ValueType,
-          typename Extractor = VarStreamArrayExtractor<ValueType>>
-
-class VarStreamArray {
-  friend class VarStreamArrayIterator<ValueType, Extractor>;
-
-public:
-  typedef VarStreamArrayIterator<ValueType, Extractor> Iterator;
-
-  VarStreamArray() = default;
-  explicit VarStreamArray(const Extractor &E) : E(E) {}
-
-  explicit VarStreamArray(ReadableStreamRef Stream) : Stream(Stream) {}
-  VarStreamArray(ReadableStreamRef Stream, const Extractor &E)
-      : Stream(Stream), E(E) {}
-
-  VarStreamArray(const VarStreamArray<ValueType, Extractor> &Other)
-      : Stream(Other.Stream), E(Other.E) {}
-
-  Iterator begin(bool *HadError = nullptr) const {
-    return Iterator(*this, E, HadError);
-  }
-
-  Iterator end() const { return Iterator(E); }
-
-  const Extractor &getExtractor() const { return E; }
-
-  ReadableStreamRef getUnderlyingStream() const { return Stream; }
-
-private:
-  ReadableStreamRef Stream;
-  Extractor E;
-};
-
-template <typename ValueType, typename Extractor>
-class VarStreamArrayIterator
-    : public iterator_facade_base<VarStreamArrayIterator<ValueType, Extractor>,
-                                  std::forward_iterator_tag, ValueType> {
-  typedef VarStreamArrayIterator<ValueType, Extractor> IterType;
-  typedef VarStreamArray<ValueType, Extractor> ArrayType;
-
-public:
-  VarStreamArrayIterator(const ArrayType &Array, const Extractor &E,
-                         bool *HadError = nullptr)
-      : IterRef(Array.Stream), Array(&Array), HadError(HadError), Extract(E) {
-    if (IterRef.getLength() == 0)
-      moveToEnd();
-    else {
-      auto EC = Extract(IterRef, ThisLen, ThisValue);
-      if (EC) {
-        consumeError(std::move(EC));
-        markError();
-      }
-    }
-  }
-  VarStreamArrayIterator() = default;
-  explicit VarStreamArrayIterator(const Extractor &E) : Extract(E) {}
-  ~VarStreamArrayIterator() = default;
-
-  bool operator==(const IterType &R) const {
-    if (Array && R.Array) {
-      // Both have a valid array, make sure they're same.
-      assert(Array == R.Array);
-      return IterRef == R.IterRef;
-    }
-
-    // Both iterators are at the end.
-    if (!Array && !R.Array)
-      return true;
-
-    // One is not at the end and one is.
-    return false;
-  }
-
-  const ValueType &operator*() const {
-    assert(Array && !HasError);
-    return ThisValue;
-  }
-
-  IterType &operator++() {
-    // We are done with the current record, discard it so that we are
-    // positioned at the next record.
-    IterRef = IterRef.drop_front(ThisLen);
-    if (IterRef.getLength() == 0) {
-      // There is nothing after the current record, we must make this an end
-      // iterator.
-      moveToEnd();
-    } else {
-      // There is some data after the current record.
-      auto EC = Extract(IterRef, ThisLen, ThisValue);
-      if (EC) {
-        consumeError(std::move(EC));
-        markError();
-      } else if (ThisLen == 0) {
-        // An empty record? Make this an end iterator.
-        moveToEnd();
-      }
-    }
-    return *this;
-  }
-
-private:
-  void moveToEnd() {
-    Array = nullptr;
-    ThisLen = 0;
-  }
-  void markError() {
-    moveToEnd();
-    HasError = true;
-    if (HadError != nullptr)
-      *HadError = true;
-  }
-
-  ValueType ThisValue;
-  ReadableStreamRef IterRef;
-  const ArrayType *Array{nullptr};
-  uint32_t ThisLen{0};
-  bool HasError{false};
-  bool *HadError{nullptr};
-  Extractor Extract;
-};
-
-template <typename T> class FixedStreamArrayIterator;
-
-template <typename T> class FixedStreamArray {
-  friend class FixedStreamArrayIterator<T>;
-
-public:
-  FixedStreamArray() = default;
-  FixedStreamArray(ReadableStreamRef Stream) : Stream(Stream) {
-    assert(Stream.getLength() % sizeof(T) == 0);
-  }
-
-  bool operator==(const FixedStreamArray<T> &Other) const {
-    return Stream == Other.Stream;
-  }
-
-  bool operator!=(const FixedStreamArray<T> &Other) const {
-    return !(*this == Other);
-  }
-
-  FixedStreamArray &operator=(const FixedStreamArray &) = default;
-
-  const T &operator[](uint32_t Index) const {
-    assert(Index < size());
-    uint32_t Off = Index * sizeof(T);
-    ArrayRef<uint8_t> Data;
-    if (auto EC = Stream.readBytes(Off, sizeof(T), Data)) {
-      assert(false && "Unexpected failure reading from stream");
-      // This should never happen since we asserted that the stream length was
-      // an exact multiple of the element size.
-      consumeError(std::move(EC));
-    }
-    return *reinterpret_cast<const T *>(Data.data());
-  }
-
-  uint32_t size() const { return Stream.getLength() / sizeof(T); }
-
-  bool empty() const { return size() == 0; }
-
-  FixedStreamArrayIterator<T> begin() const {
-    return FixedStreamArrayIterator<T>(*this, 0);
-  }
-
-  FixedStreamArrayIterator<T> end() const {
-    return FixedStreamArrayIterator<T>(*this, size());
-  }
-
-  ReadableStreamRef getUnderlyingStream() const { return Stream; }
-
-private:
-  ReadableStreamRef Stream;
-};
-
-template <typename T>
-class FixedStreamArrayIterator
-    : public iterator_facade_base<FixedStreamArrayIterator<T>,
-                                  std::random_access_iterator_tag, T> {
-
-public:
-  FixedStreamArrayIterator(const FixedStreamArray<T> &Array, uint32_t Index)
-      : Array(Array), Index(Index) {}
-
-  FixedStreamArrayIterator<T> &
-  operator=(const FixedStreamArrayIterator<T> &Other) {
-    Array = Other.Array;
-    Index = Other.Index;
-    return *this;
-  }
-
-  const T &operator*() const { return Array[Index]; }
-
-  bool operator==(const FixedStreamArrayIterator<T> &R) const {
-    assert(Array == R.Array);
-    return (Index == R.Index) && (Array == R.Array);
-  }
-
-  FixedStreamArrayIterator<T> &operator+=(std::ptrdiff_t N) {
-    Index += N;
-    return *this;
-  }
-
-  FixedStreamArrayIterator<T> &operator-=(std::ptrdiff_t N) {
-    assert(Index >= N);
-    Index -= N;
-    return *this;
-  }
-
-  std::ptrdiff_t operator-(const FixedStreamArrayIterator<T> &R) const {
-    assert(Array == R.Array);
-    assert(Index >= R.Index);
-    return Index - R.Index;
-  }
-
-  bool operator<(const FixedStreamArrayIterator<T> &RHS) const {
-    assert(Array == RHS.Array);
-    return Index < RHS.Index;
-  }
-
-private:
-  FixedStreamArray<T> Array;
-  uint32_t Index;
-};
-
-} // namespace msf
-} // namespace llvm
-
-#endif // LLVM_DEBUGINFO_MSF_STREAMARRAY_H
Index: llvm/include/llvm/DebugInfo/MSF/StreamInterface.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/StreamInterface.h
+++ /dev/null
@@ -1,53 +0,0 @@
-//===- StreamInterface.h - Base interface for a stream of data --*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_DEBUGINFO_MSF_STREAMINTERFACE_H
-#define LLVM_DEBUGINFO_MSF_STREAMINTERFACE_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/Support/Error.h"
-#include <cstdint>
-
-namespace llvm {
-namespace msf {
-
-class ReadableStream {
-public:
-  virtual ~ReadableStream() = default;
-
-  // Given an offset into the stream and a number of bytes, attempt to read
-  // the bytes and set the output ArrayRef to point to a reference into the
-  // stream, without copying any data.
-  virtual Error readBytes(uint32_t Offset, uint32_t Size,
-                          ArrayRef<uint8_t> &Buffer) const = 0;
-
-  // Given an offset into the stream, read as much as possible without copying
-  // any data.
-  virtual Error readLongestContiguousChunk(uint32_t Offset,
-                                           ArrayRef<uint8_t> &Buffer) const = 0;
-
-  virtual uint32_t getLength() const = 0;
-};
-
-class WritableStream : public ReadableStream {
-public:
-  ~WritableStream() override = default;
-
-  // Attempt to write the given bytes into the stream at the desired offset.
-  // This will always necessitate a copy.  Cannot shrink or grow the stream,
-  // only writes into existing allocated space.
-  virtual Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) const = 0;
-
-  virtual Error commit() const = 0;
-};
-
-} // end namespace msf
-} // end namespace llvm
-
-#endif // LLVM_DEBUGINFO_MSF_STREAMINTERFACE_H
Index: llvm/include/llvm/DebugInfo/MSF/StreamReader.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/StreamReader.h
+++ /dev/null
@@ -1,135 +0,0 @@
-//===- StreamReader.h - Reads bytes and objects from a stream ---*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_DEBUGINFO_MSF_STREAMREADER_H
-#define LLVM_DEBUGINFO_MSF_STREAMREADER_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/DebugInfo/MSF/MSFError.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
-#include "llvm/Support/Endian.h"
-#include "llvm/Support/Error.h"
-#include "llvm/Support/type_traits.h"
-
-#include <string>
-#include <type_traits>
-
-namespace llvm {
-namespace msf {
-
-class StreamReader {
-public:
-  StreamReader(ReadableStreamRef Stream);
-
-  Error readLongestContiguousChunk(ArrayRef<uint8_t> &Buffer);
-  Error readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size);
-
-  template <typename T>
-  Error readInteger(T &Dest,
-                    llvm::support::endianness Endian = llvm::support::native) {
-    static_assert(std::is_integral<T>::value,
-                  "Cannot call readInteger with non-integral value!");
-
-    ArrayRef<uint8_t> Bytes;
-    if (auto EC = readBytes(Bytes, sizeof(T)))
-      return EC;
-
-    Dest = llvm::support::endian::read<T, llvm::support::unaligned>(
-        Bytes.data(), Endian);
-    return Error::success();
-  }
-
-  Error readZeroString(StringRef &Dest);
-  Error readFixedString(StringRef &Dest, uint32_t Length);
-  Error readStreamRef(ReadableStreamRef &Ref);
-  Error readStreamRef(ReadableStreamRef &Ref, uint32_t Length);
-
-  template <typename T>
-  Error readEnum(T &Dest,
-                 llvm::support::endianness Endian = llvm::support::native) {
-    static_assert(std::is_enum<T>::value,
-                  "Cannot call readEnum with non-enum value!");
-    typename std::underlying_type<T>::type N;
-    if (auto EC = readInteger(N, Endian))
-      return EC;
-    Dest = static_cast<T>(N);
-    return Error::success();
-  }
-
-  template <typename T> Error readObject(const T *&Dest) {
-    ArrayRef<uint8_t> Buffer;
-    if (auto EC = readBytes(Buffer, sizeof(T)))
-      return EC;
-    Dest = reinterpret_cast<const T *>(Buffer.data());
-    return Error::success();
-  }
-
-  template <typename T>
-  Error readArray(ArrayRef<T> &Array, uint32_t NumElements) {
-    ArrayRef<uint8_t> Bytes;
-    if (NumElements == 0) {
-      Array = ArrayRef<T>();
-      return Error::success();
-    }
-
-    if (NumElements > UINT32_MAX / sizeof(T))
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-
-    if (auto EC = readBytes(Bytes, NumElements * sizeof(T)))
-      return EC;
-    Array = ArrayRef<T>(reinterpret_cast<const T *>(Bytes.data()), NumElements);
-    return Error::success();
-  }
-
-  template <typename T, typename U>
-  Error readArray(VarStreamArray<T, U> &Array, uint32_t Size) {
-    ReadableStreamRef S;
-    if (auto EC = readStreamRef(S, Size))
-      return EC;
-    Array = VarStreamArray<T, U>(S, Array.getExtractor());
-    return Error::success();
-  }
-
-  template <typename T>
-  Error readArray(FixedStreamArray<T> &Array, uint32_t NumItems) {
-    if (NumItems == 0) {
-      Array = FixedStreamArray<T>();
-      return Error::success();
-    }
-    uint32_t Length = NumItems * sizeof(T);
-    if (Length / sizeof(T) != NumItems)
-      return make_error<MSFError>(msf_error_code::invalid_format);
-    if (Offset + Length > Stream.getLength())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    ReadableStreamRef View = Stream.slice(Offset, Length);
-    Array = FixedStreamArray<T>(View);
-    Offset += Length;
-    return Error::success();
-  }
-
-  bool empty() const { return bytesRemaining() == 0; }
-  void setOffset(uint32_t Off) { Offset = Off; }
-  uint32_t getOffset() const { return Offset; }
-  uint32_t getLength() const { return Stream.getLength(); }
-  uint32_t bytesRemaining() const { return getLength() - getOffset(); }
-
-  Error skip(uint32_t Amount);
-
-  uint8_t peek() const;
-
-private:
-  ReadableStreamRef Stream;
-  uint32_t Offset;
-};
-} // namespace msf
-} // namespace llvm
-
-#endif // LLVM_DEBUGINFO_MSF_STREAMREADER_H
Index: llvm/include/llvm/DebugInfo/MSF/StreamRef.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/StreamRef.h
+++ /dev/null
@@ -1,135 +0,0 @@
-//===- StreamRef.h - A copyable reference to a stream -----------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_DEBUGINFO_MSF_STREAMREF_H
-#define LLVM_DEBUGINFO_MSF_STREAMREF_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/DebugInfo/MSF/MSFError.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
-#include "llvm/Support/Error.h"
-#include <algorithm>
-#include <cstdint>
-
-namespace llvm {
-namespace msf {
-
-template <class StreamType, class RefType> class StreamRefBase {
-public:
-  StreamRefBase() : Stream(nullptr), ViewOffset(0), Length(0) {}
-  StreamRefBase(const StreamType &Stream, uint32_t Offset, uint32_t Length)
-      : Stream(&Stream), ViewOffset(Offset), Length(Length) {}
-
-  uint32_t getLength() const { return Length; }
-  const StreamType *getStream() const { return Stream; }
-
-  RefType drop_front(uint32_t N) const {
-    if (!Stream)
-      return RefType();
-
-    N = std::min(N, Length);
-    return RefType(*Stream, ViewOffset + N, Length - N);
-  }
-
-  RefType keep_front(uint32_t N) const {
-    if (!Stream)
-      return RefType();
-    N = std::min(N, Length);
-    return RefType(*Stream, ViewOffset, N);
-  }
-
-  RefType slice(uint32_t Offset, uint32_t Len) const {
-    return drop_front(Offset).keep_front(Len);
-  }
-
-  bool operator==(const RefType &Other) const {
-    if (Stream != Other.Stream)
-      return false;
-    if (ViewOffset != Other.ViewOffset)
-      return false;
-    if (Length != Other.Length)
-      return false;
-    return true;
-  }
-
-protected:
-  const StreamType *Stream;
-  uint32_t ViewOffset;
-  uint32_t Length;
-};
-
-class ReadableStreamRef
-    : public StreamRefBase<ReadableStream, ReadableStreamRef> {
-public:
-  ReadableStreamRef() = default;
-  ReadableStreamRef(const ReadableStream &Stream)
-      : StreamRefBase(Stream, 0, Stream.getLength()) {}
-  ReadableStreamRef(const ReadableStream &Stream, uint32_t Offset,
-                    uint32_t Length)
-      : StreamRefBase(Stream, Offset, Length) {}
-
-  // Use StreamRef.slice() instead.
-  ReadableStreamRef(const ReadableStreamRef &S, uint32_t Offset,
-                    uint32_t Length) = delete;
-
-  Error readBytes(uint32_t Offset, uint32_t Size,
-                  ArrayRef<uint8_t> &Buffer) const {
-    if (ViewOffset + Offset < Offset)
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    if (Size + Offset > Length)
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    return Stream->readBytes(ViewOffset + Offset, Size, Buffer);
-  }
-
-  // Given an offset into the stream, read as much as possible without copying
-  // any data.
-  Error readLongestContiguousChunk(uint32_t Offset,
-                                   ArrayRef<uint8_t> &Buffer) const {
-    if (Offset >= Length)
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-
-    if (auto EC = Stream->readLongestContiguousChunk(Offset, Buffer))
-      return EC;
-    // This StreamRef might refer to a smaller window over a larger stream.  In
-    // that case we will have read out more bytes than we should return, because
-    // we should not read past the end of the current view.
-    uint32_t MaxLength = Length - Offset;
-    if (Buffer.size() > MaxLength)
-      Buffer = Buffer.slice(0, MaxLength);
-    return Error::success();
-  }
-};
-
-class WritableStreamRef
-    : public StreamRefBase<WritableStream, WritableStreamRef> {
-public:
-  WritableStreamRef() = default;
-  WritableStreamRef(const WritableStream &Stream)
-      : StreamRefBase(Stream, 0, Stream.getLength()) {}
-  WritableStreamRef(const WritableStream &Stream, uint32_t Offset,
-                    uint32_t Length)
-      : StreamRefBase(Stream, Offset, Length) {}
-
-  // Use StreamRef.slice() instead.
-  WritableStreamRef(const WritableStreamRef &S, uint32_t Offset,
-                    uint32_t Length) = delete;
-
-  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) const {
-    if (Data.size() + Offset > Length)
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-    return Stream->writeBytes(ViewOffset + Offset, Data);
-  }
-
-  Error commit() const { return Stream->commit(); }
-};
-
-} // end namespace msf
-} // end namespace llvm
-
-#endif // LLVM_DEBUGINFO_MSF_STREAMREF_H
Index: llvm/include/llvm/DebugInfo/MSF/StreamWriter.h
===================================================================
--- llvm/include/llvm/DebugInfo/MSF/StreamWriter.h
+++ /dev/null
@@ -1,102 +0,0 @@
-//===- StreamWriter.h - Writes bytes and objects to a stream ----*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_DEBUGINFO_MSF_STREAMWRITER_H
-#define LLVM_DEBUGINFO_MSF_STREAMWRITER_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/DebugInfo/MSF/MSFError.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
-#include "llvm/Support/Endian.h"
-#include "llvm/Support/Error.h"
-#include <cstdint>
-#include <type_traits>
-
-namespace llvm {
-namespace msf {
-
-class StreamWriter {
-public:
-  StreamWriter() = default;
-  explicit StreamWriter(WritableStreamRef Stream);
-
-  Error writeBytes(ArrayRef<uint8_t> Buffer);
-
-  template <typename T>
-  Error writeInteger(T Value,
-                     llvm::support::endianness Endian = llvm::support::native) {
-    static_assert(std::is_integral<T>::value,
-                  "Cannot call writeInteger with non-integral value!");
-    uint8_t Buffer[sizeof(T)];
-    llvm::support::endian::write<T, llvm::support::unaligned>(Buffer, Value,
-                                                              Endian);
-    return writeBytes(Buffer);
-  }
-
-  Error writeZeroString(StringRef Str);
-  Error writeFixedString(StringRef Str);
-  Error writeStreamRef(ReadableStreamRef Ref);
-  Error writeStreamRef(ReadableStreamRef Ref, uint32_t Size);
-
-  template <typename T>
-  Error writeEnum(T Num,
-                  llvm::support::endianness Endian = llvm::support::native) {
-    static_assert(std::is_enum<T>::value,
-                  "Cannot call writeEnum with non-Enum type");
-
-    using U = typename std::underlying_type<T>::type;
-    return writeInteger<U>(static_cast<U>(Num), Endian);
-  }
-
-  template <typename T> Error writeObject(const T &Obj) {
-    static_assert(!std::is_pointer<T>::value,
-                  "writeObject should not be used with pointers, to write "
-                  "the pointed-to value dereference the pointer before calling "
-                  "writeObject");
-    return writeBytes(
-        ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(&Obj), sizeof(T)));
-  }
-
-  template <typename T> Error writeArray(ArrayRef<T> Array) {
-    if (Array.empty())
-      return Error::success();
-
-    if (Array.size() > UINT32_MAX / sizeof(T))
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
-
-    return writeBytes(
-        ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(Array.data()),
-                          Array.size() * sizeof(T)));
-  }
-
-  template <typename T, typename U>
-  Error writeArray(VarStreamArray<T, U> Array) {
-    return writeStreamRef(Array.getUnderlyingStream());
-  }
-
-  template <typename T> Error writeArray(FixedStreamArray<T> Array) {
-    return writeStreamRef(Array.getUnderlyingStream());
-  }
-
-  void setOffset(uint32_t Off) { Offset = Off; }
-  uint32_t getOffset() const { return Offset; }
-  uint32_t getLength() const { return Stream.getLength(); }
-  uint32_t bytesRemaining() const { return getLength() - getOffset(); }
-
-private:
-  WritableStreamRef Stream;
-  uint32_t Offset = 0;
-};
-
-} // end namespace msf
-} // end namespace llvm
-
-#endif // LLVM_DEBUGINFO_MSF_STREAMWRITER_H
Index: llvm/include/llvm/DebugInfo/PDB/Native/DbiStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/DbiStream.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/DbiStream.h
@@ -12,13 +12,13 @@
 
 #include "llvm/DebugInfo/CodeView/ModuleSubstream.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
 #include "llvm/DebugInfo/PDB/Native/ModInfo.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/DebugInfo/PDB/Native/StringTable.h"
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 
@@ -70,11 +70,11 @@
 
   Expected<StringRef> getFileNameForIndex(uint32_t Index) const;
 
-  msf::FixedStreamArray<object::coff_section> getSectionHeaders();
+  FixedStreamArray<object::coff_section> getSectionHeaders();
 
-  msf::FixedStreamArray<object::FpoData> getFpoRecords();
+  FixedStreamArray<object::FpoData> getFpoRecords();
 
-  msf::FixedStreamArray<SecMapEntry> getSectionMap() const;
+  FixedStreamArray<SecMapEntry> getSectionMap() const;
   void visitSectionContributions(ISectionContribVisitor &Visitor) const;
 
 private:
@@ -91,28 +91,28 @@
   std::vector<ModuleInfoEx> ModuleInfos;
   StringTable ECNames;
 
-  msf::ReadableStreamRef ModInfoSubstream;
-  msf::ReadableStreamRef SecContrSubstream;
-  msf::ReadableStreamRef SecMapSubstream;
-  msf::ReadableStreamRef FileInfoSubstream;
-  msf::ReadableStreamRef TypeServerMapSubstream;
-  msf::ReadableStreamRef ECSubstream;
+  BinaryStreamRef ModInfoSubstream;
+  BinaryStreamRef SecContrSubstream;
+  BinaryStreamRef SecMapSubstream;
+  BinaryStreamRef FileInfoSubstream;
+  BinaryStreamRef TypeServerMapSubstream;
+  BinaryStreamRef ECSubstream;
 
-  msf::ReadableStreamRef NamesBuffer;
+  BinaryStreamRef NamesBuffer;
 
-  msf::FixedStreamArray<support::ulittle16_t> DbgStreams;
+  FixedStreamArray<support::ulittle16_t> DbgStreams;
 
   PdbRaw_DbiSecContribVer SectionContribVersion;
-  msf::FixedStreamArray<SectionContrib> SectionContribs;
-  msf::FixedStreamArray<SectionContrib2> SectionContribs2;
-  msf::FixedStreamArray<SecMapEntry> SectionMap;
-  msf::FixedStreamArray<support::little32_t> FileNameOffsets;
+  FixedStreamArray<SectionContrib> SectionContribs;
+  FixedStreamArray<SectionContrib2> SectionContribs2;
+  FixedStreamArray<SecMapEntry> SectionMap;
+  FixedStreamArray<support::little32_t> FileNameOffsets;
 
   std::unique_ptr<msf::MappedBlockStream> SectionHeaderStream;
-  msf::FixedStreamArray<object::coff_section> SectionHeaders;
+  FixedStreamArray<object::coff_section> SectionHeaders;
 
   std::unique_ptr<msf::MappedBlockStream> FpoStream;
-  msf::FixedStreamArray<object::FpoData> FpoRecords;
+  FixedStreamArray<object::FpoData> FpoRecords;
 
   const DbiStreamHeader *Header;
 };
Index: llvm/include/llvm/DebugInfo/PDB/Native/DbiStreamBuilder.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/DbiStreamBuilder.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/DbiStreamBuilder.h
@@ -14,11 +14,11 @@
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Error.h"
 
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Endian.h"
 
 namespace llvm {
@@ -60,7 +60,7 @@
 
   Error finalizeMsfLayout();
 
-  Error commit(const msf::MSFLayout &Layout, const msf::WritableStream &Buffer);
+  Error commit(const msf::MSFLayout &Layout, WritableBinaryStreamRef Buffer);
 
   // A helper function to create Section Contributions from COFF input
   // section headers.
@@ -112,9 +112,9 @@
 
   StringMap<uint32_t> SourceFileNames;
 
-  msf::WritableStreamRef NamesBuffer;
-  msf::MutableByteStream ModInfoBuffer;
-  msf::MutableByteStream FileInfoBuffer;
+  WritableBinaryStreamRef NamesBuffer;
+  MutableBinaryByteStream ModInfoBuffer;
+  MutableBinaryByteStream FileInfoBuffer;
   ArrayRef<SectionContrib> SectionContribs;
   ArrayRef<SecMapEntry> SectionMap;
   llvm::SmallVector<DebugStream, (int)DbgHeaderType::Max> DbgStreams;
Index: llvm/include/llvm/DebugInfo/PDB/Native/GlobalsStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/GlobalsStream.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/GlobalsStream.h
@@ -11,10 +11,10 @@
 #define LLVM_DEBUGINFO_PDB_RAW_GLOBALS_STREAM_H
 
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
@@ -27,15 +27,15 @@
   explicit GlobalsStream(std::unique_ptr<msf::MappedBlockStream> Stream);
   ~GlobalsStream();
   Error commit();
-  msf::FixedStreamArray<support::ulittle32_t> getHashBuckets() const {
+  FixedStreamArray<support::ulittle32_t> getHashBuckets() const {
     return HashBuckets;
   }
   uint32_t getNumBuckets() const { return NumBuckets; }
   Error reload();
 
 private:
-  msf::FixedStreamArray<support::ulittle32_t> HashBuckets;
-  msf::FixedStreamArray<PSHashRecord> HashRecords;
+  FixedStreamArray<support::ulittle32_t> HashBuckets;
+  FixedStreamArray<PSHashRecord> HashRecords;
   uint32_t NumBuckets;
   std::unique_ptr<msf::MappedBlockStream> Stream;
 };
Index: llvm/include/llvm/DebugInfo/PDB/Native/HashTable.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/HashTable.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/HashTable.h
@@ -14,9 +14,9 @@
 #include "llvm/ADT/SparseBitVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MathExtras.h"
@@ -42,10 +42,10 @@
   HashTable();
   explicit HashTable(uint32_t Capacity);
 
-  Error load(msf::StreamReader &Stream);
+  Error load(BinaryStreamReader &Stream);
 
   uint32_t calculateSerializedLength() const;
-  Error commit(msf::StreamWriter &Writer) const;
+  Error commit(BinaryStreamWriter &Writer) const;
 
   void clear();
 
@@ -71,9 +71,9 @@
   static uint32_t maxLoad(uint32_t capacity);
   void grow();
 
-  static Error readSparseBitVector(msf::StreamReader &Stream,
+  static Error readSparseBitVector(BinaryStreamReader &Stream,
                                    SparseBitVector<> &V);
-  static Error writeSparseBitVector(msf::StreamWriter &Writer,
+  static Error writeSparseBitVector(BinaryStreamWriter &Writer,
                                     SparseBitVector<> &Vec);
 };
 
Index: llvm/include/llvm/DebugInfo/PDB/Native/InfoStreamBuilder.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/InfoStreamBuilder.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/InfoStreamBuilder.h
@@ -19,9 +19,10 @@
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
 
 namespace llvm {
+class WritableBinaryStream;
+
 namespace msf {
 class MSFBuilder;
-class StreamWriter;
 }
 namespace pdb {
 class PDBFile;
@@ -43,7 +44,7 @@
   Error finalizeMsfLayout();
 
   Error commit(const msf::MSFLayout &Layout,
-               const msf::WritableStream &Buffer) const;
+               WritableBinaryStreamRef Buffer) const;
 
 private:
   msf::MSFBuilder &Msf;
Index: llvm/include/llvm/DebugInfo/PDB/Native/ModInfo.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/ModInfo.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/ModInfo.h
@@ -11,9 +11,9 @@
 #define LLVM_DEBUGINFO_PDB_RAW_MODINFO_H
 
 #include "llvm/ADT/StringRef.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Error.h"
 #include <cstdint>
 #include <vector>
@@ -30,7 +30,7 @@
   ModInfo(const ModInfo &Info);
   ~ModInfo();
 
-  static Error initialize(msf::ReadableStreamRef Stream, ModInfo &Info);
+  static Error initialize(BinaryStreamRef Stream, ModInfo &Info);
 
   bool hasECInfo() const;
   uint16_t getTypeServerIndex() const;
@@ -63,10 +63,8 @@
 
 } // end namespace pdb
 
-namespace msf {
-
 template <> struct VarStreamArrayExtractor<pdb::ModInfo> {
-  Error operator()(ReadableStreamRef Stream, uint32_t &Length,
+  Error operator()(BinaryStreamRef Stream, uint32_t &Length,
                    pdb::ModInfo &Info) const {
     if (auto EC = pdb::ModInfo::initialize(Stream, Info))
       return EC;
@@ -75,8 +73,6 @@
   }
 };
 
-} // end namespace msf
-
 } // end namespace llvm
 
 #endif // LLVM_DEBUGINFO_PDB_RAW_MODINFO_H
Index: llvm/include/llvm/DebugInfo/PDB/Native/ModStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/ModStream.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/ModStream.h
@@ -15,8 +15,8 @@
 #include "llvm/DebugInfo/CodeView/ModuleSubstream.h"
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
@@ -50,9 +50,9 @@
   std::unique_ptr<msf::MappedBlockStream> Stream;
 
   codeview::CVSymbolArray SymbolsSubstream;
-  msf::ReadableStreamRef LinesSubstream;
-  msf::ReadableStreamRef C13LinesSubstream;
-  msf::ReadableStreamRef GlobalRefsSubstream;
+  BinaryStreamRef LinesSubstream;
+  BinaryStreamRef C13LinesSubstream;
+  BinaryStreamRef GlobalRefsSubstream;
 
   codeview::ModuleSubstreamArray LineInfo;
 };
Index: llvm/include/llvm/DebugInfo/PDB/Native/NamedStreamMap.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/NamedStreamMap.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/NamedStreamMap.h
@@ -17,10 +17,9 @@
 #include <cstdint>
 
 namespace llvm {
-namespace msf {
-class StreamReader;
-class StreamWriter;
-}
+class BinaryStreamReader;
+class BinaryStreamWriter;
+
 namespace pdb {
 class NamedStreamMapBuilder;
 class NamedStreamMap {
@@ -33,8 +32,8 @@
 public:
   NamedStreamMap();
 
-  Error load(msf::StreamReader &Stream);
-  Error commit(msf::StreamWriter &Writer) const;
+  Error load(BinaryStreamReader &Stream);
+  Error commit(BinaryStreamWriter &Writer) const;
   uint32_t finalize();
 
   bool get(StringRef Stream, uint32_t &StreamNo) const;
Index: llvm/include/llvm/DebugInfo/PDB/Native/PDBFile.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/PDBFile.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/PDBFile.h
@@ -13,9 +13,9 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/DebugInfo/MSF/IMSFFile.h"
 #include "llvm/DebugInfo/MSF/MSFCommon.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MathExtras.h"
@@ -42,7 +42,7 @@
   friend PDBFileBuilder;
 
 public:
-  PDBFile(StringRef Path, std::unique_ptr<msf::ReadableStream> PdbFileBuffer,
+  PDBFile(StringRef Path, std::unique_ptr<BinaryStream> PdbFileBuffer,
           BumpPtrAllocator &Allocator);
   ~PDBFile() override;
 
@@ -80,7 +80,7 @@
   }
 
   const msf::MSFLayout &getMsfLayout() const { return ContainerLayout; }
-  const msf::ReadableStream &getMsfBuffer() const { return *Buffer; }
+  BinaryStreamRef getMsfBuffer() const { return *Buffer; }
 
   ArrayRef<support::ulittle32_t> getDirectoryBlockArray() const;
 
@@ -110,13 +110,13 @@
 private:
   Expected<std::unique_ptr<msf::MappedBlockStream>>
   safelyCreateIndexedStream(const msf::MSFLayout &Layout,
-                            const msf::ReadableStream &MsfData,
+                            BinaryStreamRef MsfData,
                             uint32_t StreamIndex) const;
 
   std::string FilePath;
   BumpPtrAllocator &Allocator;
 
-  std::unique_ptr<msf::ReadableStream> Buffer;
+  std::unique_ptr<BinaryStream> Buffer;
 
   std::vector<uint32_t> FpmPages;
   msf::MSFLayout ContainerLayout;
Index: llvm/include/llvm/DebugInfo/PDB/Native/PublicsStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/PublicsStream.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/PublicsStream.h
@@ -12,11 +12,11 @@
 
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
 
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
@@ -38,16 +38,16 @@
   uint32_t getNumBuckets() const { return NumBuckets; }
   iterator_range<codeview::CVSymbolArray::Iterator>
   getSymbols(bool *HadError) const;
-  msf::FixedStreamArray<support::ulittle32_t> getHashBuckets() const {
+  FixedStreamArray<support::ulittle32_t> getHashBuckets() const {
     return HashBuckets;
   }
-  msf::FixedStreamArray<support::ulittle32_t> getAddressMap() const {
+  FixedStreamArray<support::ulittle32_t> getAddressMap() const {
     return AddressMap;
   }
-  msf::FixedStreamArray<support::ulittle32_t> getThunkMap() const {
+  FixedStreamArray<support::ulittle32_t> getThunkMap() const {
     return ThunkMap;
   }
-  msf::FixedStreamArray<SectionOffset> getSectionOffsets() const {
+  FixedStreamArray<SectionOffset> getSectionOffsets() const {
     return SectionOffsets;
   }
 
@@ -59,11 +59,11 @@
   std::unique_ptr<msf::MappedBlockStream> Stream;
   uint32_t NumBuckets = 0;
   ArrayRef<uint8_t> Bitmap;
-  msf::FixedStreamArray<PSHashRecord> HashRecords;
-  msf::FixedStreamArray<support::ulittle32_t> HashBuckets;
-  msf::FixedStreamArray<support::ulittle32_t> AddressMap;
-  msf::FixedStreamArray<support::ulittle32_t> ThunkMap;
-  msf::FixedStreamArray<SectionOffset> SectionOffsets;
+  FixedStreamArray<PSHashRecord> HashRecords;
+  FixedStreamArray<support::ulittle32_t> HashBuckets;
+  FixedStreamArray<support::ulittle32_t> AddressMap;
+  FixedStreamArray<support::ulittle32_t> ThunkMap;
+  FixedStreamArray<SectionOffset> SectionOffsets;
 
   const HeaderInfo *Header;
   const GSIHashHeader *HashHdr;
Index: llvm/include/llvm/DebugInfo/PDB/Native/StringTable.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/StringTable.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/StringTable.h
@@ -12,24 +12,23 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cstdint>
 #include <vector>
 
 namespace llvm {
-namespace msf {
-class StreamReader;
-}
+class BinaryStreamReader;
+
 namespace pdb {
 
 class StringTable {
 public:
   StringTable();
 
-  Error load(msf::StreamReader &Stream);
+  Error load(BinaryStreamReader &Stream);
 
   uint32_t getNameCount() const { return NameCount; }
   uint32_t getHashVersion() const { return HashVersion; }
@@ -38,11 +37,11 @@
   StringRef getStringForID(uint32_t ID) const;
   uint32_t getIDForString(StringRef Str) const;
 
-  msf::FixedStreamArray<support::ulittle32_t> name_ids() const;
+  FixedStreamArray<support::ulittle32_t> name_ids() const;
 
 private:
-  msf::ReadableStreamRef NamesBuffer;
-  msf::FixedStreamArray<support::ulittle32_t> IDs;
+  BinaryStreamRef NamesBuffer;
+  FixedStreamArray<support::ulittle32_t> IDs;
   uint32_t Signature;
   uint32_t HashVersion;
   uint32_t NameCount;
Index: llvm/include/llvm/DebugInfo/PDB/Native/StringTableBuilder.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/StringTableBuilder.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/StringTableBuilder.h
@@ -20,9 +20,8 @@
 #include <vector>
 
 namespace llvm {
-namespace msf {
-class StreamWriter;
-}
+class BinaryStreamWriter;
+
 namespace pdb {
 
 class StringTableBuilder {
@@ -32,7 +31,7 @@
   uint32_t insert(StringRef S);
 
   uint32_t finalize();
-  Error commit(msf::StreamWriter &Writer) const;
+  Error commit(BinaryStreamWriter &Writer) const;
 
 private:
   DenseMap<StringRef, uint32_t> Strings;
Index: llvm/include/llvm/DebugInfo/PDB/Native/TpiHashing.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/TpiHashing.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/TpiHashing.h
@@ -15,8 +15,8 @@
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cstdint>
@@ -57,7 +57,7 @@
 
 class TpiHashVerifier : public codeview::TypeVisitorCallbacks {
 public:
-  TpiHashVerifier(msf::FixedStreamArray<support::ulittle32_t> &HashValues,
+  TpiHashVerifier(FixedStreamArray<support::ulittle32_t> &HashValues,
                   uint32_t NumHashBuckets)
       : HashValues(HashValues), NumHashBuckets(NumHashBuckets) {}
 
@@ -83,7 +83,7 @@
             utohexstr(codeview::TypeIndex::FirstNonSimpleIndex + Index));
   }
 
-  msf::FixedStreamArray<support::ulittle32_t> HashValues;
+  FixedStreamArray<support::ulittle32_t> HashValues;
   codeview::CVType RawRecord;
   uint32_t NumHashBuckets;
   uint32_t Index = -1;
Index: llvm/include/llvm/DebugInfo/PDB/Native/TpiStream.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/TpiStream.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/TpiStream.h
@@ -11,11 +11,12 @@
 #define LLVM_DEBUGINFO_PDB_RAW_PDBTPISTREAM_H
 
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
 #include "llvm/DebugInfo/PDB/Native/HashTable.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include "llvm/Support/Error.h"
@@ -46,8 +47,8 @@
 
   uint32_t getHashKeySize() const;
   uint32_t NumHashBuckets() const;
-  msf::FixedStreamArray<support::ulittle32_t> getHashValues() const;
-  msf::FixedStreamArray<TypeIndexOffset> getTypeIndexOffsets() const;
+  FixedStreamArray<support::ulittle32_t> getHashValues() const;
+  FixedStreamArray<TypeIndexOffset> getTypeIndexOffsets() const;
   HashTable &getHashAdjusters();
 
   codeview::CVTypeRange types(bool *HadError) const;
@@ -62,9 +63,9 @@
 
   codeview::CVTypeArray TypeRecords;
 
-  std::unique_ptr<msf::ReadableStream> HashStream;
-  msf::FixedStreamArray<support::ulittle32_t> HashValues;
-  msf::FixedStreamArray<TypeIndexOffset> TypeIndexOffsets;
+  std::unique_ptr<BinaryStream> HashStream;
+  FixedStreamArray<support::ulittle32_t> HashValues;
+  FixedStreamArray<TypeIndexOffset> TypeIndexOffsets;
   HashTable HashAdjusters;
 
   const TpiStreamHeader *Header;
Index: llvm/include/llvm/DebugInfo/PDB/Native/TpiStreamBuilder.h
===================================================================
--- llvm/include/llvm/DebugInfo/PDB/Native/TpiStreamBuilder.h
+++ llvm/include/llvm/DebugInfo/PDB/Native/TpiStreamBuilder.h
@@ -12,31 +12,31 @@
 
 #include "llvm/ADT/Optional.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/SequencedItemStream.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryItemStream.h"
 #include "llvm/Support/Error.h"
 
 #include <vector>
 
 namespace llvm {
-namespace codeview {
-class TypeRecord;
-}
-namespace msf {
-class ByteStream;
-class MSFBuilder;
-struct MSFLayout;
-class ReadableStreamRef;
-class WritableStream;
+class BinaryStreamRef;
+class WritableBinaryStream;
 
-template <> struct SequencedItemTraits<llvm::codeview::CVType> {
+template <> struct BinaryItemTraits<llvm::codeview::CVType> {
   static size_t length(const codeview::CVType &Item) { return Item.length(); }
   static ArrayRef<uint8_t> bytes(const codeview::CVType &Item) {
     return Item.data();
   }
 };
+
+namespace codeview {
+class TypeRecord;
+}
+namespace msf {
+class MSFBuilder;
+struct MSFLayout;
 }
 namespace pdb {
 class PDBFile;
@@ -56,9 +56,9 @@
 
   Error finalizeMsfLayout();
 
-  Error commit(const msf::MSFLayout &Layout, const msf::WritableStream &Buffer);
+  Error commit(const msf::MSFLayout &Layout, WritableBinaryStreamRef Buffer);
 
-  uint32_t calculateSerializedLength() const;
+  uint32_t calculateSerializedLength();
 
 private:
   uint32_t calculateHashBufferSize() const;
@@ -69,9 +69,9 @@
 
   Optional<PdbRaw_TpiVer> VerHeader;
   std::vector<codeview::CVType> TypeRecords;
-  msf::SequencedItemStream<codeview::CVType> TypeRecordStream;
+  BinaryItemStream<codeview::CVType> TypeRecordStream;
   uint32_t HashStreamIndex = kInvalidStreamIndex;
-  std::unique_ptr<msf::ByteStream> HashValueStream;
+  std::unique_ptr<BinaryByteStream> HashValueStream;
 
   const TpiStreamHeader *Header;
   uint32_t Idx;
Index: llvm/include/llvm/Support/BinaryByteStream.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/BinaryByteStream.h
@@ -0,0 +1,176 @@
+//===- BinaryByteStream.h ---------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//===----------------------------------------------------------------------===//
+// A BinaryStream which stores data in a single continguous memory buffer.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYBYTESTREAM_H
+#define LLVM_SUPPORT_BINARYBYTESTREAM_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include <algorithm>
+#include <cstdint>
+#include <cstring>
+#include <memory>
+
+namespace llvm {
+
+/// \brief An implementation of BinaryStream which holds its entire data set
+/// in a single contiguous buffer.  BinaryByteStream guarantees that no read
+/// operation will ever incur a copy.  Note that BinaryByteStream does not
+/// own the underlying buffer.
+class BinaryByteStream : public BinaryStream {
+public:
+  BinaryByteStream() = default;
+  explicit BinaryByteStream(ArrayRef<uint8_t> Data) : Data(Data) {}
+  explicit BinaryByteStream(StringRef Data)
+      : Data(Data.bytes_begin(), Data.bytes_end()) {}
+
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) override {
+    if (Offset > Data.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    if (Data.size() < Size + Offset)
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    Buffer = Data.slice(Offset, Size);
+    return Error::success();
+  }
+
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) override {
+    if (Offset >= Data.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    Buffer = Data.slice(Offset);
+    return Error::success();
+  }
+
+  uint32_t getLength() override { return Data.size(); }
+
+  ArrayRef<uint8_t> data() const { return Data; }
+
+  StringRef str() const {
+    const char *CharData = reinterpret_cast<const char *>(Data.data());
+    return StringRef(CharData, Data.size());
+  }
+
+protected:
+  ArrayRef<uint8_t> Data;
+};
+
+/// \brief An implementation of BinaryStream whose data is backed by an llvm
+/// MemoryBuffer object.  MemoryBufferByteStream owns the MemoryBuffer in
+/// question.  As with BinaryByteStream, reading from a MemoryBufferByteStream
+/// will never cause a copy.
+class MemoryBufferByteStream : public BinaryByteStream {
+public:
+  explicit MemoryBufferByteStream(std::unique_ptr<MemoryBuffer> Buffer)
+      : BinaryByteStream(makeArrayRef(Buffer->getBuffer().bytes())),
+        MemBuffer(std::move(Buffer)) {}
+
+  std::unique_ptr<MemoryBuffer> MemBuffer;
+};
+
+/// \brief An implementation of BinaryStream which holds its entire data set
+/// in a single contiguous buffer.  As with BinaryByteStream, the mutable
+/// version also guarantees that no read operation will ever incur a copy,
+/// and similarly it does not own the underlying buffer.
+class MutableBinaryByteStream : public WritableBinaryStream {
+public:
+  MutableBinaryByteStream() = default;
+  explicit MutableBinaryByteStream(MutableArrayRef<uint8_t> Data)
+      : Data(Data), ImmutableStream(Data) {}
+
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) override {
+    return ImmutableStream.readBytes(Offset, Size, Buffer);
+  }
+
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) override {
+    return ImmutableStream.readLongestContiguousChunk(Offset, Buffer);
+  }
+
+  uint32_t getLength() override { return ImmutableStream.getLength(); }
+
+  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Buffer) override {
+    if (Buffer.empty())
+      return Error::success();
+
+    if (Data.size() < Buffer.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    if (Offset > Buffer.size() - Data.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+
+    uint8_t *DataPtr = const_cast<uint8_t *>(Data.data());
+    ::memcpy(DataPtr + Offset, Buffer.data(), Buffer.size());
+    return Error::success();
+  }
+
+  Error commit() override { return Error::success(); }
+
+  MutableArrayRef<uint8_t> data() const { return Data; }
+
+private:
+  MutableArrayRef<uint8_t> Data;
+  BinaryByteStream ImmutableStream;
+};
+
+/// \brief An implementation of WritableBinaryStream backed by an llvm
+/// FileOutputBuffer.
+class FileBufferByteStream : public WritableBinaryStream {
+private:
+  class StreamImpl : public MutableBinaryByteStream {
+  public:
+    StreamImpl(std::unique_ptr<FileOutputBuffer> Buffer)
+        : MutableBinaryByteStream(MutableArrayRef<uint8_t>(
+              Buffer->getBufferStart(), Buffer->getBufferEnd())),
+          FileBuffer(std::move(Buffer)) {}
+
+    Error commit() override {
+      if (FileBuffer->commit())
+        return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+      return Error::success();
+    }
+
+  private:
+    std::unique_ptr<FileOutputBuffer> FileBuffer;
+  };
+
+public:
+  explicit FileBufferByteStream(std::unique_ptr<FileOutputBuffer> Buffer)
+      : Impl(std::move(Buffer)) {}
+
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) override {
+    return Impl.readBytes(Offset, Size, Buffer);
+  }
+
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) override {
+    return Impl.readLongestContiguousChunk(Offset, Buffer);
+  }
+
+  uint32_t getLength() override { return Impl.getLength(); }
+
+  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) override {
+    return Impl.writeBytes(Offset, Data);
+  }
+
+  Error commit() override { return Impl.commit(); }
+
+private:
+  StreamImpl Impl;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYBYTESTREAM_H
Index: llvm/include/llvm/Support/BinaryItemStream.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/BinaryItemStream.h
@@ -0,0 +1,98 @@
+//===- BinaryItemStream.h ---------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYITEMSTREAM_H
+#define LLVM_SUPPORT_BINARYITEMSTREAM_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/Error.h"
+#include <cstddef>
+#include <cstdint>
+
+namespace llvm {
+
+template <typename T> struct BinaryItemTraits {
+  size_t length(const T &Item) = delete;
+  ArrayRef<uint8_t> bytes(const T &Item) = delete;
+};
+
+/// BinaryItemStream represents a sequence of objects stored in some kind of
+/// external container but for which it is useful to view as a stream of
+/// contiguous bytes.  An example of this might be if you have a collection of
+/// records and you serialize each one into a buffer, and store these serialized
+/// records in a container.  The pointers themselves are not laid out
+/// contiguously in memory, but we may wish to read from or write to these
+/// records as if they were.
+template <typename T, typename ItemTraits = BinaryItemTraits<T>>
+class BinaryItemStream : public BinaryStream {
+public:
+  BinaryItemStream() = default;
+
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) override {
+    if (auto EC = readLongestContiguousChunk(Offset, Buffer))
+      return EC;
+
+    if (Size > Buffer.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+
+    Buffer = Buffer.take_front(Size);
+    return Error::success();
+  }
+
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) override {
+    uint32_t Index;
+    uint32_t ByteOffset;
+    if (auto EC = translateOffsetIndex(Offset, Index, ByteOffset))
+      return EC;
+    const auto &Item = Items[Index];
+    Buffer = Traits.bytes(Item).drop_front(ByteOffset);
+    return Error::success();
+  }
+
+  void setItems(ArrayRef<T> ItemArray) { Items = ItemArray; }
+
+  uint32_t getLength() override {
+    uint32_t Size = 0;
+    for (const auto &Item : Items)
+      Size += Traits.length(Item);
+    return Size;
+  }
+
+private:
+  Error translateOffsetIndex(uint32_t Offset, uint32_t &ItemIndex,
+                             uint32_t &ByteOffset) {
+    ItemIndex = 0;
+    ByteOffset = 0;
+    uint32_t PrevOffset = 0;
+    uint32_t CurrentOffset = 0;
+    if (Offset > 0) {
+      for (const auto &Item : Items) {
+        PrevOffset = CurrentOffset;
+        CurrentOffset += Traits.length(Item);
+        if (CurrentOffset > Offset)
+          break;
+        ++ItemIndex;
+      }
+    }
+    if (CurrentOffset < Offset)
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    ByteOffset = Offset - PrevOffset;
+    return Error::success();
+  }
+
+  ItemTraits Traits;
+  ArrayRef<T> Items;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYITEMSTREAM_H
Index: llvm/include/llvm/Support/BinaryStream.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/BinaryStream.h
@@ -0,0 +1,65 @@
+//===- BinaryStream.h - Base interface for a stream of data -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYSTREAM_H
+#define LLVM_SUPPORT_BINARYSTREAM_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/Error.h"
+#include <cstdint>
+
+namespace llvm {
+
+/// \brief An interface for accessing data in a stream-like format, but which
+/// discourages copying.  Instead of specifying a buffer in which to copy
+/// data on a read, the API returns an ArrayRef to data owned by the stream's
+/// implementation.  Since implementations may not necessarily store data in a
+/// single contiguous buffer (or even in memory at all), in such cases a it may
+/// be necessary for an implementation to cache such a buffer so that it can
+/// return it.
+class BinaryStream {
+public:
+  virtual ~BinaryStream() = default;
+
+  /// \brief Given an offset into the stream and a number of bytes, attempt to
+  /// read the bytes and set the output ArrayRef to point to data owned by the
+  /// stream.
+  virtual Error readBytes(uint32_t Offset, uint32_t Size,
+                          ArrayRef<uint8_t> &Buffer) = 0;
+
+  /// \brief Given an offset into the stream, read as much as possible without
+  /// copying any data.
+  virtual Error readLongestContiguousChunk(uint32_t Offset,
+                                           ArrayRef<uint8_t> &Buffer) = 0;
+
+  /// \brief Return the number of bytes of data in this stream.
+  virtual uint32_t getLength() = 0;
+};
+
+/// \brief A BinaryStream which can be read from as well as written to.  Note
+/// that writing to a BinaryStream always necessitates copying from the input
+/// buffer to the stream's backing store.  Streams are assumed to be buffered
+/// so that to be portable it is necessary to call commit() on the stream when
+/// all data has been written.
+class WritableBinaryStream : public BinaryStream {
+public:
+  ~WritableBinaryStream() override = default;
+
+  /// \brief Attempt to write the given bytes into the stream at the desired
+  /// offset. This will always necessitate a copy.  Cannot shrink or grow the
+  /// stream, only writes into existing allocated space.
+  virtual Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) = 0;
+
+  /// \brief For buffered streams, commits changes to the backing store.
+  virtual Error commit() = 0;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYSTREAM_H
Index: llvm/include/llvm/Support/BinaryStreamArray.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/BinaryStreamArray.h
@@ -0,0 +1,319 @@
+//===- BinaryStreamArray.h - Array backed by an arbitrary stream *- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYSTREAMARRAY_H
+#define LLVM_SUPPORT_BINARYSTREAMARRAY_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/Error.h"
+#include <cassert>
+#include <cstdint>
+
+/// Lightweight arrays that are backed by an arbitrary BinaryStream.  This file
+/// provides two different array implementations.
+///
+///     VarStreamArray - Arrays of variable length records.  The user specifies
+///       an Extractor type that can extract a record from a given offset and
+///       return the number of bytes consumed by the record.
+///
+///     FixedStreamArray - Arrays of fixed length records.  This is similar in
+///       spirit to ArrayRef<T>, but since it is backed by a BinaryStream, the
+///       elements of the array need not be laid out in contiguous memory.
+namespace llvm {
+
+/// VarStreamArrayExtractor is intended to be specialized to provide customized
+/// extraction logic.  On input it receives a BinaryStreamRef pointing to the
+/// beginning of the next record, but where the length of the record is not yet
+/// known.  Upon completion, it should return an appropriate Error instance if
+/// a record could not be extracted, or if one could be extracted it should
+/// return success and set Len to the number of bytes this record occupied in
+/// the underlying stream, and it should fill out the fields of the value type
+/// Item appropriately to represent the current record.
+///
+/// You can specialize this template for your own custom value types to avoid
+/// having to specify a second template argument to VarStreamArray (documented
+/// below).
+template <typename T> struct VarStreamArrayExtractor {
+  // Method intentionally deleted.  You must provide an explicit specialization
+  // with the following method implemented.
+  Error operator()(BinaryStreamRef Stream, uint32_t &Len,
+                   T &Item) const = delete;
+};
+
+/// VarStreamArray represents an array of variable length records backed by a
+/// stream.  This could be a contiguous sequence of bytes in memory, it could
+/// be a file on disk, or it could be a PDB stream where bytes are stored as
+/// discontiguous blocks in a file.  Usually it is desirable to treat arrays
+/// as contiguous blocks of memory, but doing so with large PDB files, for
+/// example, could mean allocating huge amounts of memory just to allow
+/// re-ordering of stream data to be contiguous before iterating over it.  By
+/// abstracting this out, we need not duplicate this memory, and we can
+/// iterate over arrays in arbitrarily formatted streams.  Elements are parsed
+/// lazily on iteration, so there is no upfront cost associated with building
+/// or copying a VarStreamArray, no matter how large it may be.
+///
+/// You create a VarStreamArray by specifying a ValueType and an Extractor type.
+/// If you do not specify an Extractor type, you are expected to specialize
+/// VarStreamArrayExtractor<T> for your ValueType.
+///
+/// By default an Extractor is default constructed in the class, but in some
+/// cases you might find it useful for an Extractor to maintain state across
+/// extractions.  In this case you can provide your own Extractor through a
+/// secondary constructor.  The following examples show various ways of
+/// creating a VarStreamArray.
+///
+///       // Will use VarStreamArrayExtractor<MyType> as the extractor.
+///       VarStreamArray<MyType> MyTypeArray;
+///
+///       // Will use a default-constructed MyExtractor as the extractor.
+///       VarStreamArray<MyType, MyExtractor> MyTypeArray2;
+///
+///       // Will use the specific instance of MyExtractor provided.
+///       // MyExtractor need not be default-constructible in this case.
+///       MyExtractor E(SomeContext);
+///       VarStreamArray<MyType, MyExtractor> MyTypeArray3(E);
+///
+template <typename ValueType, typename Extractor> class VarStreamArrayIterator;
+
+template <typename ValueType,
+          typename Extractor = VarStreamArrayExtractor<ValueType>>
+
+class VarStreamArray {
+  friend class VarStreamArrayIterator<ValueType, Extractor>;
+
+public:
+  typedef VarStreamArrayIterator<ValueType, Extractor> Iterator;
+
+  VarStreamArray() = default;
+  explicit VarStreamArray(const Extractor &E) : E(E) {}
+
+  explicit VarStreamArray(BinaryStreamRef Stream) : Stream(Stream) {}
+  VarStreamArray(BinaryStreamRef Stream, const Extractor &E)
+      : Stream(Stream), E(E) {}
+
+  VarStreamArray(const VarStreamArray<ValueType, Extractor> &Other)
+      : Stream(Other.Stream), E(Other.E) {}
+
+  Iterator begin(bool *HadError = nullptr) const {
+    return Iterator(*this, E, HadError);
+  }
+
+  Iterator end() const { return Iterator(E); }
+
+  const Extractor &getExtractor() const { return E; }
+
+  BinaryStreamRef getUnderlyingStream() const { return Stream; }
+
+private:
+  BinaryStreamRef Stream;
+  Extractor E;
+};
+
+template <typename ValueType, typename Extractor>
+class VarStreamArrayIterator
+    : public iterator_facade_base<VarStreamArrayIterator<ValueType, Extractor>,
+                                  std::forward_iterator_tag, ValueType> {
+  typedef VarStreamArrayIterator<ValueType, Extractor> IterType;
+  typedef VarStreamArray<ValueType, Extractor> ArrayType;
+
+public:
+  VarStreamArrayIterator(const ArrayType &Array, const Extractor &E,
+                         bool *HadError = nullptr)
+      : IterRef(Array.Stream), Array(&Array), HadError(HadError), Extract(E) {
+    if (IterRef.getLength() == 0)
+      moveToEnd();
+    else {
+      auto EC = Extract(IterRef, ThisLen, ThisValue);
+      if (EC) {
+        consumeError(std::move(EC));
+        markError();
+      }
+    }
+  }
+  VarStreamArrayIterator() = default;
+  explicit VarStreamArrayIterator(const Extractor &E) : Extract(E) {}
+  ~VarStreamArrayIterator() = default;
+
+  bool operator==(const IterType &R) const {
+    if (Array && R.Array) {
+      // Both have a valid array, make sure they're same.
+      assert(Array == R.Array);
+      return IterRef == R.IterRef;
+    }
+
+    // Both iterators are at the end.
+    if (!Array && !R.Array)
+      return true;
+
+    // One is not at the end and one is.
+    return false;
+  }
+
+  const ValueType &operator*() const {
+    assert(Array && !HasError);
+    return ThisValue;
+  }
+
+  IterType &operator+=(unsigned N) {
+    for (unsigned I = 0; I < N; ++I) {
+      // We are done with the current record, discard it so that we are
+      // positioned at the next record.
+      IterRef = IterRef.drop_front(ThisLen);
+      if (IterRef.getLength() == 0) {
+        // There is nothing after the current record, we must make this an end
+        // iterator.
+        moveToEnd();
+      } else {
+        // There is some data after the current record.
+        auto EC = Extract(IterRef, ThisLen, ThisValue);
+        if (EC) {
+          consumeError(std::move(EC));
+          markError();
+        } else if (ThisLen == 0) {
+          // An empty record? Make this an end iterator.
+          moveToEnd();
+        }
+      }
+    }
+    return *this;
+  }
+
+private:
+  void moveToEnd() {
+    Array = nullptr;
+    ThisLen = 0;
+  }
+  void markError() {
+    moveToEnd();
+    HasError = true;
+    if (HadError != nullptr)
+      *HadError = true;
+  }
+
+  ValueType ThisValue;
+  BinaryStreamRef IterRef;
+  const ArrayType *Array{nullptr};
+  uint32_t ThisLen{0};
+  bool HasError{false};
+  bool *HadError{nullptr};
+  Extractor Extract;
+};
+
+template <typename T> class FixedStreamArrayIterator;
+
+/// FixedStreamArray is similar to VarStreamArray, except with each record
+/// having a fixed-length.  As with VarStreamArray, there is no upfront
+/// cost associated with building or copying a FixedStreamArray, as the
+/// memory for each element is not read from the backing stream until that
+/// element is iterated.
+template <typename T> class FixedStreamArray {
+  friend class FixedStreamArrayIterator<T>;
+
+public:
+  FixedStreamArray() = default;
+  explicit FixedStreamArray(BinaryStreamRef Stream) : Stream(Stream) {
+    assert(Stream.getLength() % sizeof(T) == 0);
+  }
+
+  bool operator==(const FixedStreamArray<T> &Other) const {
+    return Stream == Other.Stream;
+  }
+
+  bool operator!=(const FixedStreamArray<T> &Other) const {
+    return !(*this == Other);
+  }
+
+  FixedStreamArray &operator=(const FixedStreamArray &) = default;
+
+  const T &operator[](uint32_t Index) const {
+    assert(Index < size());
+    uint32_t Off = Index * sizeof(T);
+    ArrayRef<uint8_t> Data;
+    if (auto EC = Stream.readBytes(Off, sizeof(T), Data)) {
+      assert(false && "Unexpected failure reading from stream");
+      // This should never happen since we asserted that the stream length was
+      // an exact multiple of the element size.
+      consumeError(std::move(EC));
+    }
+    return *reinterpret_cast<const T *>(Data.data());
+  }
+
+  uint32_t size() const { return Stream.getLength() / sizeof(T); }
+
+  bool empty() const { return size() == 0; }
+
+  FixedStreamArrayIterator<T> begin() const {
+    return FixedStreamArrayIterator<T>(*this, 0);
+  }
+
+  FixedStreamArrayIterator<T> end() const {
+    return FixedStreamArrayIterator<T>(*this, size());
+  }
+
+  BinaryStreamRef getUnderlyingStream() const { return Stream; }
+
+private:
+  BinaryStreamRef Stream;
+};
+
+template <typename T>
+class FixedStreamArrayIterator
+    : public iterator_facade_base<FixedStreamArrayIterator<T>,
+                                  std::random_access_iterator_tag, T> {
+
+public:
+  FixedStreamArrayIterator(const FixedStreamArray<T> &Array, uint32_t Index)
+      : Array(Array), Index(Index) {}
+
+  FixedStreamArrayIterator<T> &
+  operator=(const FixedStreamArrayIterator<T> &Other) {
+    Array = Other.Array;
+    Index = Other.Index;
+    return *this;
+  }
+
+  const T &operator*() const { return Array[Index]; }
+
+  bool operator==(const FixedStreamArrayIterator<T> &R) const {
+    assert(Array == R.Array);
+    return (Index == R.Index) && (Array == R.Array);
+  }
+
+  FixedStreamArrayIterator<T> &operator+=(std::ptrdiff_t N) {
+    Index += N;
+    return *this;
+  }
+
+  FixedStreamArrayIterator<T> &operator-=(std::ptrdiff_t N) {
+    assert(Index >= N);
+    Index -= N;
+    return *this;
+  }
+
+  std::ptrdiff_t operator-(const FixedStreamArrayIterator<T> &R) const {
+    assert(Array == R.Array);
+    assert(Index >= R.Index);
+    return Index - R.Index;
+  }
+
+  bool operator<(const FixedStreamArrayIterator<T> &RHS) const {
+    assert(Array == RHS.Array);
+    return Index < RHS.Index;
+  }
+
+private:
+  FixedStreamArray<T> Array;
+  uint32_t Index;
+};
+
+} // namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYSTREAMARRAY_H
Index: llvm/include/llvm/Support/BinaryStreamReader.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/BinaryStreamReader.h
@@ -0,0 +1,228 @@
+//===- BinaryStreamReader.h - Reads objects from a binary stream *- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYSTREAMREADER_H
+#define LLVM_SUPPORT_BINARYSTREAMREADER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/type_traits.h"
+
+#include <string>
+#include <type_traits>
+
+namespace llvm {
+
+/// \brief Provides read only access to a subclass of `BinaryStream`.  Provides
+/// bounds checking and helpers for writing certain common data types such as
+/// null-terminated strings, integers in various flavors of endianness, etc.
+/// Can be subclassed to provide reading of custom datatypes, although no
+/// are overridable.
+class BinaryStreamReader {
+public:
+  BinaryStreamReader(BinaryStreamRef Stream, llvm::support::endianness Endian);
+  virtual ~BinaryStreamReader() {}
+
+  /// Read as much as possible from the underlying string at the current offset
+  /// without invoking a copy, and set \p Buffer to the resulting data slice.
+  /// Updates the stream's offset to point after the newly read data.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  Error readLongestContiguousChunk(ArrayRef<uint8_t> &Buffer);
+
+  /// Read \p Size bytes from the underlying stream at the current offset and
+  /// and set \p Buffer to the resulting data slice.  Whether a copy occurs
+  /// depends on the implementation of the underlying stream.  Updates the
+  /// stream's offset to point after the newly read data.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  Error readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size);
+
+  /// Read an integer of the specified endianness into \p Dest and update the
+  /// stream's offset.  The data is always copied from the stream's underlying
+  /// buffer into \p Dest. Updates the stream's offset to point after the newly
+  /// read data.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  template <typename T> Error readInteger(T &Dest) {
+    static_assert(std::is_integral<T>::value,
+                  "Cannot call readInteger with non-integral value!");
+
+    ArrayRef<uint8_t> Bytes;
+    if (auto EC = readBytes(Bytes, sizeof(T)))
+      return EC;
+
+    Dest = llvm::support::endian::read<T, llvm::support::unaligned>(
+        Bytes.data(), Endian);
+    return Error::success();
+  }
+
+  /// Similar to readInteger.
+  template <typename T> Error readEnum(T &Dest) {
+    static_assert(std::is_enum<T>::value,
+                  "Cannot call readEnum with non-enum value!");
+    typename std::underlying_type<T>::type N;
+    if (auto EC = readInteger(N))
+      return EC;
+    Dest = static_cast<T>(N);
+    return Error::success();
+  }
+
+  /// Read a null terminated string from \p Dest.  Whether a copy occurs depends
+  /// on the implementation of the underlying stream.  Updates the stream's
+  /// offset to point after the newly read data.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  Error readZeroString(StringRef &Dest);
+
+  /// Read a \p Length byte string into \p Dest.  Whether a copy occurs depends
+  /// on the implementation of the underlying stream.  Updates the stream's
+  /// offset to point after the newly read data.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  Error readFixedString(StringRef &Dest, uint32_t Length);
+
+  /// Read the entire remainder of the underlying stream into \p Ref.  This is
+  /// equivalent to calling getUnderlyingStream().slice(Offset).  Updates the
+  /// stream's offset to point to the end of the stream.  Never causes a copy.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  Error readStreamRef(BinaryStreamRef &Ref);
+
+  /// Read \p Length bytes from the underlying stream into \p Ref.  This is
+  /// equivalent to calling getUnderlyingStream().slice(Offset, Length).
+  /// Updates the stream's offset to point after the newly read object.  Never
+  /// causes a copy.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  Error readStreamRef(BinaryStreamRef &Ref, uint32_t Length);
+
+  /// Get a pointer to an object of type T from the underlying stream, as if by
+  /// memcpy, and store the result into \p Dest.  It is up to the caller to
+  /// ensure that objects of type T can be safely treated in this manner.
+  /// Updates the stream's offset to point after the newly read object.  Whether
+  /// a copy occurs depends upon the implementation of the underlying
+  /// stream.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  template <typename T> Error readObject(const T *&Dest) {
+    ArrayRef<uint8_t> Buffer;
+    if (auto EC = readBytes(Buffer, sizeof(T)))
+      return EC;
+    Dest = reinterpret_cast<const T *>(Buffer.data());
+    return Error::success();
+  }
+
+  /// Get a reference to a \p NumElements element array of objects of type T
+  /// from the underlying stream as if by memcpy, and store the resulting array
+  /// slice into \p array.  It is up to the caller to ensure that objects of
+  /// type T can be safely treated in this manner.  Updates the stream's offset
+  /// to point after the newly read object.  Whether a copy occurs depends upon
+  /// the implementation of the underlying stream.
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  template <typename T>
+  Error readArray(ArrayRef<T> &Array, uint32_t NumElements) {
+    ArrayRef<uint8_t> Bytes;
+    if (NumElements == 0) {
+      Array = ArrayRef<T>();
+      return Error::success();
+    }
+
+    if (NumElements > UINT32_MAX / sizeof(T))
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+
+    if (auto EC = readBytes(Bytes, NumElements * sizeof(T)))
+      return EC;
+    Array = ArrayRef<T>(reinterpret_cast<const T *>(Bytes.data()), NumElements);
+    return Error::success();
+  }
+
+  /// Read a VarStreamArray of size \p Size bytes and store the result into
+  /// \p Array.  Updates the stream's offset to point after the newly read
+  /// array.  Never causes a copy (although iterating the elements of the
+  /// VarStreamArray may, depending upon the implementation of the underlying
+  /// stream).
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  template <typename T, typename U>
+  Error readArray(VarStreamArray<T, U> &Array, uint32_t Size) {
+    BinaryStreamRef S;
+    if (auto EC = readStreamRef(S, Size))
+      return EC;
+    Array = VarStreamArray<T, U>(S, Array.getExtractor());
+    return Error::success();
+  }
+
+  /// Read a FixedStreamArray of \p NumItems elements and store the result into
+  /// \p Array.  Updates the stream's offset to point after the newly read
+  /// array.  Never causes a copy (although iterating the elements of the
+  /// FixedStreamArray may, depending upon the implementation of the underlying
+  /// stream).
+  ///
+  /// \returns a success error code if the data was successfully read, otherwise
+  /// returns an appropriate error code.
+  template <typename T>
+  Error readArray(FixedStreamArray<T> &Array, uint32_t NumItems) {
+    if (NumItems == 0) {
+      Array = FixedStreamArray<T>();
+      return Error::success();
+    }
+    uint32_t Length = NumItems * sizeof(T);
+    if (Length / sizeof(T) != NumItems)
+      return errorCodeToError(
+          make_error_code(std::errc::illegal_byte_sequence));
+    if (Offset + Length > Stream.getLength())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    BinaryStreamRef View = Stream.slice(Offset, Length);
+    Array = FixedStreamArray<T>(View);
+    Offset += Length;
+    return Error::success();
+  }
+
+  bool empty() const { return bytesRemaining() == 0; }
+  void setOffset(uint32_t Off) { Offset = Off; }
+  uint32_t getOffset() const { return Offset; }
+  uint32_t getLength() const { return Stream.getLength(); }
+  uint32_t bytesRemaining() const { return getLength() - getOffset(); }
+
+  /// Advance the stream's offset by \p Amount bytes.
+  ///
+  /// \returns a success error code if at least \p Amount bytes remain in the
+  /// stream, otherwise returns an appropriate error code.
+  Error skip(uint32_t Amount);
+
+  /// Examine the next byte of the underlying stream without advancing the
+  /// stream's offset.  If the stream is empty the behavior is undefined.
+  ///
+  /// \returns the next byte in the stream.
+  uint8_t peek() const;
+
+private:
+  BinaryStreamRef Stream;
+  uint32_t Offset;
+  llvm::support::endianness Endian;
+};
+} // namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYSTREAMREADER_H
Index: llvm/include/llvm/Support/BinaryStreamRef.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/BinaryStreamRef.h
@@ -0,0 +1,162 @@
+//===- BinaryStreamRef.h - A copyable reference to a stream -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYSTREAMREF_H
+#define LLVM_SUPPORT_BINARYSTREAMREF_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/Error.h"
+#include <algorithm>
+#include <cstdint>
+
+namespace llvm {
+
+/// Common stuff for mutable and immutable StreamRefs.
+template <class StreamType, class RefType> class BinaryStreamRefBase {
+public:
+  BinaryStreamRefBase() : Stream(nullptr), ViewOffset(0), Length(0) {}
+  BinaryStreamRefBase(StreamType &Stream, uint32_t Offset, uint32_t Length)
+      : Stream(&Stream), ViewOffset(Offset), Length(Length) {}
+
+  uint32_t getLength() const { return Length; }
+  const StreamType *getStream() const { return Stream; }
+
+  /// Return a new BinaryStreamRef with the first \p N elements removed.
+  RefType drop_front(uint32_t N) const {
+    if (!Stream)
+      return RefType();
+
+    N = std::min(N, Length);
+    return RefType(*Stream, ViewOffset + N, Length - N);
+  }
+
+  /// Return a new BinaryStreamRef with only the first \p N elements remaining.
+  RefType keep_front(uint32_t N) const {
+    if (!Stream)
+      return RefType();
+    N = std::min(N, Length);
+    return RefType(*Stream, ViewOffset, N);
+  }
+
+  /// Return a new BinaryStreamRef with the first \p Offset elements removed,
+  /// and retaining exactly \p Len elements.
+  RefType slice(uint32_t Offset, uint32_t Len) const {
+    return drop_front(Offset).keep_front(Len);
+  }
+
+  bool operator==(const RefType &Other) const {
+    if (Stream != Other.Stream)
+      return false;
+    if (ViewOffset != Other.ViewOffset)
+      return false;
+    if (Length != Other.Length)
+      return false;
+    return true;
+  }
+
+protected:
+  StreamType *Stream;
+  uint32_t ViewOffset;
+  uint32_t Length;
+};
+
+/// \brief BinaryStreamRef is to BinaryStream what ArrayRef is to an Array.  It
+/// provides copy-semantics and read only access to a "window" of the underlying
+/// BinaryStream. Note that BinaryStreamRef is *not* a BinaryStream.  That is to
+/// say, it does not inherit and override the methods of BinaryStream.  In
+/// general, you should not pass around pointers or references to BinaryStreams
+/// and use inheritance to achieve polymorphism.  Instead, you should pass
+/// around BinaryStreamRefs by value and achieve polymorphism that way.
+class BinaryStreamRef
+    : public BinaryStreamRefBase<BinaryStream, BinaryStreamRef> {
+public:
+  BinaryStreamRef() = default;
+  BinaryStreamRef(BinaryStream &Stream)
+      : BinaryStreamRefBase(Stream, 0, Stream.getLength()) {}
+  BinaryStreamRef(BinaryStream &Stream, uint32_t Offset, uint32_t Length)
+      : BinaryStreamRefBase(Stream, Offset, Length) {}
+
+  // Use BinaryStreamRef.slice() instead.
+  BinaryStreamRef(BinaryStreamRef &S, uint32_t Offset,
+                  uint32_t Length) = delete;
+
+  /// Given an Offset into this StreamRef and a Size, return a reference to a
+  /// buffer owned by the stream.
+  ///
+  /// \returns a success error code if the entire range of data is within the
+  /// bounds of this BinaryStreamRef's view and the implementation could read
+  /// the data, and an appropriate error code otherwise.
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) const {
+    if (ViewOffset + Offset < Offset)
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    if (Size + Offset > Length)
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    return Stream->readBytes(ViewOffset + Offset, Size, Buffer);
+  }
+
+  /// Given an Offset into this BinaryStreamRef, return a reference to the
+  /// largest buffer the stream could support without necessitating a copy.
+  ///
+  /// \returns a success error code if implementation could read the data,
+  /// and an appropriate error code otherwise.
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) const {
+    if (Offset >= Length)
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+
+    if (auto EC = Stream->readLongestContiguousChunk(Offset, Buffer))
+      return EC;
+    // This StreamRef might refer to a smaller window over a larger stream.  In
+    // that case we will have read out more bytes than we should return, because
+    // we should not read past the end of the current view.
+    uint32_t MaxLength = Length - Offset;
+    if (Buffer.size() > MaxLength)
+      Buffer = Buffer.slice(0, MaxLength);
+    return Error::success();
+  }
+};
+
+class WritableBinaryStreamRef
+    : public BinaryStreamRefBase<WritableBinaryStream,
+                                 WritableBinaryStreamRef> {
+public:
+  WritableBinaryStreamRef() = default;
+  WritableBinaryStreamRef(WritableBinaryStream &Stream)
+      : BinaryStreamRefBase(Stream, 0, Stream.getLength()) {}
+  WritableBinaryStreamRef(WritableBinaryStream &Stream, uint32_t Offset,
+                          uint32_t Length)
+      : BinaryStreamRefBase(Stream, Offset, Length) {}
+
+  // Use WritableBinaryStreamRef.slice() instead.
+  WritableBinaryStreamRef(WritableBinaryStreamRef &S, uint32_t Offset,
+                          uint32_t Length) = delete;
+
+  /// Given an Offset into this WritableBinaryStreamRef and some input data,
+  /// writes the data to the underlying stream.
+  ///
+  /// \returns a success error code if the data could fit within the underlying
+  /// stream at the specified location and the implementation could write the
+  /// data, and an appropriate error code otherwise.
+  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) const {
+    if (Data.size() + Offset > Length)
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    return Stream->writeBytes(ViewOffset + Offset, Data);
+  }
+
+  operator BinaryStreamRef() { return BinaryStreamRef(*Stream); }
+
+  /// \brief For buffered streams, commits changes to the backing store.
+  Error commit() { return Stream->commit(); }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYSTREAMREF_H
Index: llvm/include/llvm/Support/BinaryStreamWriter.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/BinaryStreamWriter.h
@@ -0,0 +1,165 @@
+//===- BinaryStreamWriter.h - Writes objects to a BinaryStream ----*- C++
+//-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_BINARYSTREAMWRITER_H
+#define LLVM_SUPPORT_BINARYSTREAMWRITER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Error.h"
+#include <cstdint>
+#include <type_traits>
+
+namespace llvm {
+
+/// \brief Provides write only access to a subclass of `WritableBinaryStream`.
+/// Provides bounds checking and helpers for writing certain common data types
+/// such as null-terminated strings, integers in various flavors of endianness,
+/// etc.  Can be subclassed to provide reading and writing of custom datatypes,
+/// although no methods are overridable.
+class BinaryStreamWriter {
+public:
+  BinaryStreamWriter() = default;
+  BinaryStreamWriter(WritableBinaryStreamRef Stream,
+                     llvm::support::endianness Endian);
+  virtual ~BinaryStreamWriter() {}
+
+  /// Write the bytes specified in \p Buffer to the underlying stream.
+  /// On success, updates the offset so that subsequent writes will occur
+  /// at the next unwritten position.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  Error writeBytes(ArrayRef<uint8_t> Buffer);
+
+  /// Write the the integer \p Value to the underlying stream in the
+  /// specified endianness.  On success, updates the offset so that
+  /// subsequent writes occur at the next unwritten position.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  template <typename T> Error writeInteger(T Value) {
+    static_assert(std::is_integral<T>::value,
+                  "Cannot call writeInteger with non-integral value!");
+    uint8_t Buffer[sizeof(T)];
+    llvm::support::endian::write<T, llvm::support::unaligned>(Buffer, Value,
+                                                              Endian);
+    return writeBytes(Buffer);
+  }
+
+  /// Similar to writeInteger
+  template <typename T> Error writeEnum(T Num) {
+    static_assert(std::is_enum<T>::value,
+                  "Cannot call writeEnum with non-Enum type");
+
+    using U = typename std::underlying_type<T>::type;
+    return writeInteger<U>(static_cast<U>(Num));
+  }
+
+  /// Write the the string \p Str to the underlying stream followed by a null
+  /// terminator.  On success, updates the offset so that subsequent writes
+  /// occur at the next unwritten position.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  Error writeZeroString(StringRef Str);
+
+  /// Write the the string \p Str to the underlying stream without a null
+  /// terminator.  On success, updates the offset so that subsequent writes
+  /// occur at the next unwritten position.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  Error writeFixedString(StringRef Str);
+
+  /// Efficiently reads all data from \p Ref, and writes it to this stream.
+  /// This operation will not invoke any copies of the source data, regardless
+  /// of the source stream's implementation.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  Error writeStreamRef(BinaryStreamRef Ref);
+
+  /// Efficiently reads \p Size bytes from \p Ref, and writes it to this stream.
+  /// This operation will not invoke any copies of the source data, regardless
+  /// of the source stream's implementation.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  Error writeStreamRef(BinaryStreamRef Ref, uint32_t Size);
+
+  /// Writes the object \p Obj to the underlying stream, as if by using memcpy.
+  /// It is up to the caller to ensure that type of \p Obj can be safely copied
+  /// in this fashion, as no checks are made to ensure that this is safe.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  template <typename T> Error writeObject(const T &Obj) {
+    static_assert(!std::is_pointer<T>::value,
+                  "writeObject should not be used with pointers, to write "
+                  "the pointed-to value dereference the pointer before calling "
+                  "writeObject");
+    return writeBytes(
+        ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(&Obj), sizeof(T)));
+  }
+
+  /// Writes an array of objects of type T to the underlying stream, as if by
+  /// using memcpy.  It is up to the caller to ensure that type of \p Obj can
+  /// be safely copied in this fashion, as no checks are made to ensure that
+  /// this is safe.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  template <typename T> Error writeArray(ArrayRef<T> Array) {
+    if (Array.empty())
+      return Error::success();
+
+    if (Array.size() > UINT32_MAX / sizeof(T))
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+
+    return writeBytes(
+        ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(Array.data()),
+                          Array.size() * sizeof(T)));
+  }
+
+  /// Writes all data from the array \p Array to the underlying stream.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  template <typename T, typename U>
+  Error writeArray(VarStreamArray<T, U> Array) {
+    return writeStreamRef(Array.getUnderlyingStream());
+  }
+
+  /// Writes all elements from the array \p Array to the underlying stream.
+  ///
+  /// \returns a success error code if the data was successfully written,
+  /// otherwise returns an appropriate error code.
+  template <typename T> Error writeArray(FixedStreamArray<T> Array) {
+    return writeStreamRef(Array.getUnderlyingStream());
+  }
+
+  void setOffset(uint32_t Off) { Offset = Off; }
+  uint32_t getOffset() const { return Offset; }
+  uint32_t getLength() const { return Stream.getLength(); }
+  uint32_t bytesRemaining() const { return getLength() - getOffset(); }
+
+protected:
+  WritableBinaryStreamRef Stream;
+  uint32_t Offset = 0;
+  llvm::support::endianness Endian;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_BINARYSTREAMWRITER_H
Index: llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -23,13 +23,13 @@
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCSectionCOFF.h"
 #include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/COFF.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Target/TargetFrameLowering.h"
@@ -38,7 +38,6 @@
 
 using namespace llvm;
 using namespace llvm::codeview;
-using namespace llvm::msf;
 
 CodeViewDebug::CodeViewDebug(AsmPrinter *AP)
     : DebugHandlerBase(AP), OS(*Asm->OutStreamer), Allocator(),
@@ -495,9 +494,9 @@
       // comments. The MSVC linker doesn't do much type record validation,
       // so the first link of an invalid type record can succeed while
       // subsequent links will fail with LNK1285.
-      ByteStream Stream(Record);
+      BinaryByteStream Stream(Record);
       CVTypeArray Types;
-      StreamReader Reader(Stream);
+      BinaryStreamReader Reader(Stream, llvm::support::little);
       Error E = Reader.readArray(Types, Reader.getLength());
       if (!E) {
         TypeVisitorCallbacks C;
Index: llvm/lib/DebugInfo/CodeView/CVSymbolVisitor.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/CVSymbolVisitor.cpp
+++ llvm/lib/DebugInfo/CodeView/CVSymbolVisitor.cpp
@@ -11,7 +11,6 @@
 
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
 #include "llvm/DebugInfo/CodeView/SymbolVisitorCallbacks.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
Index: llvm/lib/DebugInfo/CodeView/CVTypeDumper.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/CVTypeDumper.cpp
+++ llvm/lib/DebugInfo/CodeView/CVTypeDumper.cpp
@@ -14,7 +14,7 @@
 #include "llvm/DebugInfo/CodeView/TypeDeserializer.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbackPipeline.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
+#include "llvm/Support/BinaryByteStream.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -56,9 +56,9 @@
 }
 
 Error CVTypeDumper::dump(ArrayRef<uint8_t> Data, TypeVisitorCallbacks &Dumper) {
-  msf::ByteStream Stream(Data);
+  BinaryByteStream Stream(Data);
   CVTypeArray Types;
-  msf::StreamReader Reader(Stream);
+  BinaryStreamReader Reader(Stream, llvm::support::little);
   if (auto EC = Reader.readArray(Types, Reader.getLength()))
     return EC;
 
Index: llvm/lib/DebugInfo/CodeView/CVTypeVisitor.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/CVTypeVisitor.cpp
+++ llvm/lib/DebugInfo/CodeView/CVTypeVisitor.cpp
@@ -16,8 +16,8 @@
 #include "llvm/DebugInfo/CodeView/TypeRecordMapping.h"
 #include "llvm/DebugInfo/CodeView/TypeServerHandler.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbackPipeline.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -174,7 +174,7 @@
   return Error::success();
 }
 
-Error CVTypeVisitor::visitFieldListMemberStream(msf::StreamReader Reader) {
+Error CVTypeVisitor::visitFieldListMemberStream(BinaryStreamReader Reader) {
   FieldListDeserializer Deserializer(Reader);
   TypeVisitorCallbackPipeline Pipeline;
   Pipeline.addCallbackToPipeline(Deserializer);
@@ -182,7 +182,7 @@
 
   TypeLeafKind Leaf;
   while (!Reader.empty()) {
-    if (auto EC = Reader.readEnum(Leaf, llvm::support::little))
+    if (auto EC = Reader.readEnum(Leaf))
       return EC;
 
     CVMemberRecord Record;
@@ -195,7 +195,7 @@
 }
 
 Error CVTypeVisitor::visitFieldListMemberStream(ArrayRef<uint8_t> Data) {
-  msf::ByteStream S(Data);
-  msf::StreamReader SR(S);
+  BinaryByteStream S(Data);
+  BinaryStreamReader SR(S, llvm::support::little);
   return visitFieldListMemberStream(SR);
 }
Index: llvm/lib/DebugInfo/CodeView/CodeViewRecordIO.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/CodeViewRecordIO.cpp
+++ llvm/lib/DebugInfo/CodeView/CodeViewRecordIO.cpp
@@ -10,8 +10,8 @@
 #include "llvm/DebugInfo/CodeView/CodeViewRecordIO.h"
 #include "llvm/DebugInfo/CodeView/CodeView.h"
 #include "llvm/DebugInfo/CodeView/RecordSerialization.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -87,14 +87,13 @@
 
 Error CodeViewRecordIO::mapInteger(TypeIndex &TypeInd) {
   if (isWriting()) {
-    if (auto EC =
-            Writer->writeInteger(TypeInd.getIndex(), llvm::support::little))
+    if (auto EC = Writer->writeInteger(TypeInd.getIndex()))
       return EC;
     return Error::success();
   }
 
   uint32_t I;
-  if (auto EC = Reader->readInteger(I, llvm::support::little))
+  if (auto EC = Reader->readInteger(I))
     return EC;
   TypeInd.setIndex(I);
   return Error::success();
@@ -177,7 +176,7 @@
       if (auto EC = mapStringZ(V))
         return EC;
     }
-    if (auto EC = Writer->writeInteger<uint8_t>(0, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint8_t>(0))
       return EC;
   } else {
     StringRef S;
@@ -195,28 +194,24 @@
 Error CodeViewRecordIO::writeEncodedSignedInteger(const int64_t &Value) {
   assert(Value < 0 && "Encoded integer is not signed!");
   if (Value >= std::numeric_limits<int8_t>::min()) {
-    if (auto EC =
-            Writer->writeInteger<uint16_t>(LF_CHAR, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(LF_CHAR))
       return EC;
-    if (auto EC = Writer->writeInteger<int8_t>(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger<int8_t>(Value))
       return EC;
   } else if (Value >= std::numeric_limits<int16_t>::min()) {
-    if (auto EC =
-            Writer->writeInteger<uint16_t>(LF_SHORT, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(LF_SHORT))
       return EC;
-    if (auto EC = Writer->writeInteger<int16_t>(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger<int16_t>(Value))
       return EC;
   } else if (Value >= std::numeric_limits<int32_t>::min()) {
-    if (auto EC =
-            Writer->writeInteger<uint16_t>(LF_LONG, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(LF_LONG))
       return EC;
-    if (auto EC = Writer->writeInteger<int32_t>(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger<int32_t>(Value))
       return EC;
   } else {
-    if (auto EC =
-            Writer->writeInteger<uint16_t>(LF_QUADWORD, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(LF_QUADWORD))
       return EC;
-    if (auto EC = Writer->writeInteger(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger(Value))
       return EC;
   }
   return Error::success();
@@ -224,25 +219,22 @@
 
 Error CodeViewRecordIO::writeEncodedUnsignedInteger(const uint64_t &Value) {
   if (Value < LF_NUMERIC) {
-    if (auto EC = Writer->writeInteger<uint16_t>(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(Value))
       return EC;
   } else if (Value <= std::numeric_limits<uint16_t>::max()) {
-    if (auto EC =
-            Writer->writeInteger<uint16_t>(LF_USHORT, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(LF_USHORT))
       return EC;
-    if (auto EC = Writer->writeInteger<uint16_t>(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(Value))
       return EC;
   } else if (Value <= std::numeric_limits<uint32_t>::max()) {
-    if (auto EC =
-            Writer->writeInteger<uint16_t>(LF_ULONG, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(LF_ULONG))
       return EC;
-    if (auto EC = Writer->writeInteger<uint32_t>(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint32_t>(Value))
       return EC;
   } else {
-    if (auto EC =
-            Writer->writeInteger<uint16_t>(LF_UQUADWORD, llvm::support::little))
+    if (auto EC = Writer->writeInteger<uint16_t>(LF_UQUADWORD))
       return EC;
-    if (auto EC = Writer->writeInteger(Value, llvm::support::little))
+    if (auto EC = Writer->writeInteger(Value))
       return EC;
   }
 
Index: llvm/lib/DebugInfo/CodeView/ModuleSubstream.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/ModuleSubstream.cpp
+++ llvm/lib/DebugInfo/CodeView/ModuleSubstream.cpp
@@ -9,22 +9,20 @@
 
 #include "llvm/DebugInfo/CodeView/ModuleSubstream.h"
 
-#include "llvm/DebugInfo/MSF/StreamReader.h"
+#include "llvm/Support/BinaryStreamReader.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
-using namespace llvm::msf;
 
 ModuleSubstream::ModuleSubstream() : Kind(ModuleSubstreamKind::None) {}
 
-ModuleSubstream::ModuleSubstream(ModuleSubstreamKind Kind,
-                                 ReadableStreamRef Data)
+ModuleSubstream::ModuleSubstream(ModuleSubstreamKind Kind, BinaryStreamRef Data)
     : Kind(Kind), Data(Data) {}
 
-Error ModuleSubstream::initialize(ReadableStreamRef Stream,
+Error ModuleSubstream::initialize(BinaryStreamRef Stream,
                                   ModuleSubstream &Info) {
   const ModuleSubsectionHeader *Header;
-  StreamReader Reader(Stream);
+  BinaryStreamReader Reader(Stream, llvm::support::little);
   if (auto EC = Reader.readObject(Header))
     return EC;
 
@@ -42,4 +40,4 @@
 
 ModuleSubstreamKind ModuleSubstream::getSubstreamKind() const { return Kind; }
 
-ReadableStreamRef ModuleSubstream::getRecordData() const { return Data; }
+BinaryStreamRef ModuleSubstream::getRecordData() const { return Data; }
Index: llvm/lib/DebugInfo/CodeView/ModuleSubstreamVisitor.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/ModuleSubstreamVisitor.cpp
+++ llvm/lib/DebugInfo/CodeView/ModuleSubstreamVisitor.cpp
@@ -8,54 +8,52 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/CodeView/ModuleSubstreamVisitor.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
-using namespace llvm::msf;
 
-Error IModuleSubstreamVisitor::visitSymbols(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitSymbols(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::Symbols, Data);
 }
-Error IModuleSubstreamVisitor::visitLines(ReadableStreamRef Data,
+Error IModuleSubstreamVisitor::visitLines(BinaryStreamRef Data,
                                           const LineSubstreamHeader *Header,
                                           const LineInfoArray &Lines) {
   return visitUnknown(ModuleSubstreamKind::Lines, Data);
 }
-Error IModuleSubstreamVisitor::visitStringTable(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitStringTable(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::StringTable, Data);
 }
 Error IModuleSubstreamVisitor::visitFileChecksums(
-    ReadableStreamRef Data, const FileChecksumArray &Checksums) {
+    BinaryStreamRef Data, const FileChecksumArray &Checksums) {
   return visitUnknown(ModuleSubstreamKind::FileChecksums, Data);
 }
-Error IModuleSubstreamVisitor::visitFrameData(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitFrameData(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::FrameData, Data);
 }
-Error IModuleSubstreamVisitor::visitInlineeLines(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitInlineeLines(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::InlineeLines, Data);
 }
-Error IModuleSubstreamVisitor::visitCrossScopeImports(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitCrossScopeImports(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::CrossScopeExports, Data);
 }
-Error IModuleSubstreamVisitor::visitCrossScopeExports(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitCrossScopeExports(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::CrossScopeImports, Data);
 }
-Error IModuleSubstreamVisitor::visitILLines(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitILLines(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::ILLines, Data);
 }
-Error IModuleSubstreamVisitor::visitFuncMDTokenMap(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitFuncMDTokenMap(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::FuncMDTokenMap, Data);
 }
-Error IModuleSubstreamVisitor::visitTypeMDTokenMap(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitTypeMDTokenMap(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::TypeMDTokenMap, Data);
 }
-Error IModuleSubstreamVisitor::visitMergedAssemblyInput(
-    ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitMergedAssemblyInput(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::MergedAssemblyInput, Data);
 }
-Error IModuleSubstreamVisitor::visitCoffSymbolRVA(ReadableStreamRef Data) {
+Error IModuleSubstreamVisitor::visitCoffSymbolRVA(BinaryStreamRef Data) {
   return visitUnknown(ModuleSubstreamKind::CoffSymbolRVA, Data);
 }
 
@@ -65,7 +63,7 @@
   case ModuleSubstreamKind::Symbols:
     return V.visitSymbols(R.getRecordData());
   case ModuleSubstreamKind::Lines: {
-    StreamReader Reader(R.getRecordData());
+    BinaryStreamReader Reader(R.getRecordData(), llvm::support::little);
     const LineSubstreamHeader *Header;
     if (auto EC = Reader.readObject(Header))
       return EC;
@@ -78,7 +76,7 @@
   case ModuleSubstreamKind::StringTable:
     return V.visitStringTable(R.getRecordData());
   case ModuleSubstreamKind::FileChecksums: {
-    StreamReader Reader(R.getRecordData());
+    BinaryStreamReader Reader(R.getRecordData(), llvm::support::little);
     FileChecksumArray Checksums;
     if (auto EC = Reader.readArray(Checksums, Reader.bytesRemaining()))
       return EC;
Index: llvm/lib/DebugInfo/CodeView/RecordSerialization.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/RecordSerialization.cpp
+++ llvm/lib/DebugInfo/CodeView/RecordSerialization.cpp
@@ -16,7 +16,7 @@
 #include "llvm/ADT/APSInt.h"
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
+#include "llvm/Support/BinaryByteStream.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -33,11 +33,11 @@
   return getBytesAsCharacters(LeafData).split('\0').first;
 }
 
-Error llvm::codeview::consume(msf::StreamReader &Reader, APSInt &Num) {
+Error llvm::codeview::consume(BinaryStreamReader &Reader, APSInt &Num) {
   // Used to avoid overload ambiguity on APInt construtor.
   bool FalseVal = false;
   uint16_t Short;
-  if (auto EC = Reader.readInteger(Short, llvm::support::little))
+  if (auto EC = Reader.readInteger(Short))
     return EC;
 
   if (Short < LF_NUMERIC) {
@@ -49,49 +49,49 @@
   switch (Short) {
   case LF_CHAR: {
     int8_t N;
-    if (auto EC = Reader.readInteger(N, llvm::support::little))
+    if (auto EC = Reader.readInteger(N))
       return EC;
     Num = APSInt(APInt(8, N, true), false);
     return Error::success();
   }
   case LF_SHORT: {
     int16_t N;
-    if (auto EC = Reader.readInteger(N, llvm::support::little))
+    if (auto EC = Reader.readInteger(N))
       return EC;
     Num = APSInt(APInt(16, N, true), false);
     return Error::success();
   }
   case LF_USHORT: {
     uint16_t N;
-    if (auto EC = Reader.readInteger(N, llvm::support::little))
+    if (auto EC = Reader.readInteger(N))
       return EC;
     Num = APSInt(APInt(16, N, false), true);
     return Error::success();
   }
   case LF_LONG: {
     int32_t N;
-    if (auto EC = Reader.readInteger(N, llvm::support::little))
+    if (auto EC = Reader.readInteger(N))
       return EC;
     Num = APSInt(APInt(32, N, true), false);
     return Error::success();
   }
   case LF_ULONG: {
     uint32_t N;
-    if (auto EC = Reader.readInteger(N, llvm::support::little))
+    if (auto EC = Reader.readInteger(N))
       return EC;
     Num = APSInt(APInt(32, N, FalseVal), true);
     return Error::success();
   }
   case LF_QUADWORD: {
     int64_t N;
-    if (auto EC = Reader.readInteger(N, llvm::support::little))
+    if (auto EC = Reader.readInteger(N))
       return EC;
     Num = APSInt(APInt(64, N, true), false);
     return Error::success();
   }
   case LF_UQUADWORD: {
     uint64_t N;
-    if (auto EC = Reader.readInteger(N, llvm::support::little))
+    if (auto EC = Reader.readInteger(N))
       return EC;
     Num = APSInt(APInt(64, N, false), true);
     return Error::success();
@@ -103,15 +103,15 @@
 
 Error llvm::codeview::consume(StringRef &Data, APSInt &Num) {
   ArrayRef<uint8_t> Bytes(Data.bytes_begin(), Data.bytes_end());
-  msf::ByteStream S(Bytes);
-  msf::StreamReader SR(S);
+  BinaryByteStream S(Bytes);
+  BinaryStreamReader SR(S, llvm::support::little);
   auto EC = consume(SR, Num);
   Data = Data.take_back(SR.bytesRemaining());
   return EC;
 }
 
 /// Decode a numeric leaf value that is known to be a uint64_t.
-Error llvm::codeview::consume_numeric(msf::StreamReader &Reader,
+Error llvm::codeview::consume_numeric(BinaryStreamReader &Reader,
                                       uint64_t &Num) {
   APSInt N;
   if (auto EC = consume(Reader, N))
@@ -123,24 +123,24 @@
   return Error::success();
 }
 
-Error llvm::codeview::consume(msf::StreamReader &Reader, uint32_t &Item) {
-  return Reader.readInteger(Item, llvm::support::little);
+Error llvm::codeview::consume(BinaryStreamReader &Reader, uint32_t &Item) {
+  return Reader.readInteger(Item);
 }
 
 Error llvm::codeview::consume(StringRef &Data, uint32_t &Item) {
   ArrayRef<uint8_t> Bytes(Data.bytes_begin(), Data.bytes_end());
-  msf::ByteStream S(Bytes);
-  msf::StreamReader SR(S);
+  BinaryByteStream S(Bytes);
+  BinaryStreamReader SR(S, llvm::support::little);
   auto EC = consume(SR, Item);
   Data = Data.take_back(SR.bytesRemaining());
   return EC;
 }
 
-Error llvm::codeview::consume(msf::StreamReader &Reader, int32_t &Item) {
-  return Reader.readInteger(Item, llvm::support::little);
+Error llvm::codeview::consume(BinaryStreamReader &Reader, int32_t &Item) {
+  return Reader.readInteger(Item);
 }
 
-Error llvm::codeview::consume(msf::StreamReader &Reader, StringRef &Item) {
+Error llvm::codeview::consume(BinaryStreamReader &Reader, StringRef &Item) {
   if (Reader.empty())
     return make_error<CodeViewError>(cv_error_code::corrupt_record,
                                      "Null terminated string buffer is empty!");
Index: llvm/lib/DebugInfo/CodeView/TypeDumpVisitor.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/TypeDumpVisitor.cpp
+++ llvm/lib/DebugInfo/CodeView/TypeDumpVisitor.cpp
@@ -19,7 +19,6 @@
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbackPipeline.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/ScopedPrinter.h"
 
Index: llvm/lib/DebugInfo/CodeView/TypeRecord.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/TypeRecord.cpp
+++ llvm/lib/DebugInfo/CodeView/TypeRecord.cpp
@@ -10,8 +10,8 @@
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/RecordSerialization.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
Index: llvm/lib/DebugInfo/CodeView/TypeSerializer.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/TypeSerializer.cpp
+++ llvm/lib/DebugInfo/CodeView/TypeSerializer.cpp
@@ -9,7 +9,7 @@
 
 #include "llvm/DebugInfo/CodeView/TypeSerializer.h"
 
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 
 #include <string.h>
 
@@ -76,7 +76,7 @@
   int N = PaddingBytes;
   while (PaddingBytes > 0) {
     uint8_t Pad = static_cast<uint8_t>(LF_PAD0 + PaddingBytes);
-    if (auto EC = Writer.writeInteger(Pad, llvm::support::little))
+    if (auto EC = Writer.writeInteger(Pad))
       return std::move(EC);
     --PaddingBytes;
   }
@@ -85,8 +85,8 @@
 
 TypeSerializer::TypeSerializer(BumpPtrAllocator &Storage)
     : RecordStorage(Storage), LastTypeIndex(),
-      RecordBuffer(MaxRecordLength * 2), Stream(RecordBuffer), Writer(Stream),
-      Mapping(Writer) {
+      RecordBuffer(MaxRecordLength * 2), Stream(RecordBuffer),
+      Writer(Stream, llvm::support::little), Mapping(Writer) {
   // RecordBuffer needs to be able to hold enough data so that if we are 1
   // byte short of MaxRecordLen, and then we try to write MaxRecordLen bytes,
   // we won't overflow.
@@ -203,15 +203,15 @@
 
     uint8_t *SegmentBytes = RecordStorage.Allocate<uint8_t>(LengthWithSize);
     auto SavedSegment = MutableArrayRef<uint8_t>(SegmentBytes, LengthWithSize);
-    msf::MutableByteStream CS(SavedSegment);
-    msf::StreamWriter CW(CS);
+    MutableBinaryByteStream CS(SavedSegment);
+    BinaryStreamWriter CW(CS, llvm::support::little);
     if (auto EC = CW.writeBytes(CopyData))
       return EC;
-    if (auto EC = CW.writeEnum(TypeLeafKind::LF_INDEX, llvm::support::little))
+    if (auto EC = CW.writeEnum(TypeLeafKind::LF_INDEX))
       return EC;
-    if (auto EC = CW.writeInteger<uint16_t>(0, llvm::support::little))
+    if (auto EC = CW.writeInteger<uint16_t>(0))
       return EC;
-    if (auto EC = CW.writeInteger<uint32_t>(0xB0C0B0C0, llvm::support::little))
+    if (auto EC = CW.writeInteger<uint32_t>(0xB0C0B0C0))
       return EC;
     FieldListSegments.push_back(SavedSegment);
 
Index: llvm/lib/DebugInfo/MSF/CMakeLists.txt
===================================================================
--- llvm/lib/DebugInfo/MSF/CMakeLists.txt
+++ llvm/lib/DebugInfo/MSF/CMakeLists.txt
@@ -3,8 +3,6 @@
   MSFBuilder.cpp
   MSFCommon.cpp
   MSFError.cpp
-  StreamReader.cpp
-  StreamWriter.cpp
   ADDITIONAL_HEADER_DIRS
   "${LLVM_MAIN_INCLUDE_DIR}/llvm/DebugInfo/MSF"
   )
Index: llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
===================================================================
--- llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
+++ llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
@@ -47,22 +47,20 @@
 
 MappedBlockStream::MappedBlockStream(uint32_t BlockSize, uint32_t NumBlocks,
                                      const MSFStreamLayout &Layout,
-                                     const ReadableStream &MsfData)
+                                     BinaryStreamRef MsfData)
     : BlockSize(BlockSize), NumBlocks(NumBlocks), StreamLayout(Layout),
       MsfData(MsfData) {}
 
 std::unique_ptr<MappedBlockStream>
 MappedBlockStream::createStream(uint32_t BlockSize, uint32_t NumBlocks,
                                 const MSFStreamLayout &Layout,
-                                const ReadableStream &MsfData) {
+                                BinaryStreamRef MsfData) {
   return llvm::make_unique<MappedBlockStreamImpl<MappedBlockStream>>(
       BlockSize, NumBlocks, Layout, MsfData);
 }
 
-std::unique_ptr<MappedBlockStream>
-MappedBlockStream::createIndexedStream(const MSFLayout &Layout,
-                                       const ReadableStream &MsfData,
-                                       uint32_t StreamIndex) {
+std::unique_ptr<MappedBlockStream> MappedBlockStream::createIndexedStream(
+    const MSFLayout &Layout, BinaryStreamRef MsfData, uint32_t StreamIndex) {
   assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
   MSFStreamLayout SL;
   SL.Blocks = Layout.StreamMap[StreamIndex];
@@ -73,7 +71,7 @@
 
 std::unique_ptr<MappedBlockStream>
 MappedBlockStream::createDirectoryStream(const MSFLayout &Layout,
-                                         const ReadableStream &MsfData) {
+                                         BinaryStreamRef MsfData) {
   MSFStreamLayout SL;
   SL.Blocks = Layout.DirectoryBlocks;
   SL.Length = Layout.SB->NumDirectoryBytes;
@@ -82,14 +80,14 @@
 
 std::unique_ptr<MappedBlockStream>
 MappedBlockStream::createFpmStream(const MSFLayout &Layout,
-                                   const ReadableStream &MsfData) {
+                                   BinaryStreamRef MsfData) {
   MSFStreamLayout SL;
   initializeFpmStreamLayout(Layout, SL);
   return createStream(Layout.SB->BlockSize, Layout.SB->NumBlocks, SL, MsfData);
 }
 
 Error MappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
-                                   ArrayRef<uint8_t> &Buffer) const {
+                                   ArrayRef<uint8_t> &Buffer) {
   // Make sure we aren't trying to read beyond the end of the stream.
   if (Size > StreamLayout.Length)
     return make_error<MSFError>(msf_error_code::insufficient_buffer);
@@ -168,8 +166,8 @@
   return Error::success();
 }
 
-Error MappedBlockStream::readLongestContiguousChunk(
-    uint32_t Offset, ArrayRef<uint8_t> &Buffer) const {
+Error MappedBlockStream::readLongestContiguousChunk(uint32_t Offset,
+                                                    ArrayRef<uint8_t> &Buffer) {
   // Make sure we aren't trying to read beyond the end of the stream.
   if (Offset >= StreamLayout.Length)
     return make_error<MSFError>(msf_error_code::insufficient_buffer);
@@ -197,10 +195,10 @@
   return Error::success();
 }
 
-uint32_t MappedBlockStream::getLength() const { return StreamLayout.Length; }
+uint32_t MappedBlockStream::getLength() { return StreamLayout.Length; }
 
 bool MappedBlockStream::tryReadContiguously(uint32_t Offset, uint32_t Size,
-                                            ArrayRef<uint8_t> &Buffer) const {
+                                            ArrayRef<uint8_t> &Buffer) {
   if (Size == 0) {
     Buffer = ArrayRef<uint8_t>();
     return true;
@@ -241,7 +239,7 @@
 }
 
 Error MappedBlockStream::readBytes(uint32_t Offset,
-                                   MutableArrayRef<uint8_t> Buffer) const {
+                                   MutableArrayRef<uint8_t> Buffer) {
   uint32_t BlockNum = Offset / BlockSize;
   uint32_t OffsetInBlock = Offset % BlockSize;
 
@@ -319,21 +317,21 @@
 
 WritableMappedBlockStream::WritableMappedBlockStream(
     uint32_t BlockSize, uint32_t NumBlocks, const MSFStreamLayout &Layout,
-    const WritableStream &MsfData)
+    WritableBinaryStreamRef MsfData)
     : ReadInterface(BlockSize, NumBlocks, Layout, MsfData),
       WriteInterface(MsfData) {}
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createStream(uint32_t BlockSize, uint32_t NumBlocks,
                                         const MSFStreamLayout &Layout,
-                                        const WritableStream &MsfData) {
+                                        WritableBinaryStreamRef MsfData) {
   return llvm::make_unique<MappedBlockStreamImpl<WritableMappedBlockStream>>(
       BlockSize, NumBlocks, Layout, MsfData);
 }
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createIndexedStream(const MSFLayout &Layout,
-                                               const WritableStream &MsfData,
+                                               WritableBinaryStreamRef MsfData,
                                                uint32_t StreamIndex) {
   assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
   MSFStreamLayout SL;
@@ -344,7 +342,7 @@
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createDirectoryStream(
-    const MSFLayout &Layout, const WritableStream &MsfData) {
+    const MSFLayout &Layout, WritableBinaryStreamRef MsfData) {
   MSFStreamLayout SL;
   SL.Blocks = Layout.DirectoryBlocks;
   SL.Length = Layout.SB->NumDirectoryBytes;
@@ -353,28 +351,28 @@
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createFpmStream(const MSFLayout &Layout,
-                                           const WritableStream &MsfData) {
+                                           WritableBinaryStreamRef MsfData) {
   MSFStreamLayout SL;
   initializeFpmStreamLayout(Layout, SL);
   return createStream(Layout.SB->BlockSize, Layout.SB->NumBlocks, SL, MsfData);
 }
 
 Error WritableMappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
-                                           ArrayRef<uint8_t> &Buffer) const {
+                                           ArrayRef<uint8_t> &Buffer) {
   return ReadInterface.readBytes(Offset, Size, Buffer);
 }
 
 Error WritableMappedBlockStream::readLongestContiguousChunk(
-    uint32_t Offset, ArrayRef<uint8_t> &Buffer) const {
+    uint32_t Offset, ArrayRef<uint8_t> &Buffer) {
   return ReadInterface.readLongestContiguousChunk(Offset, Buffer);
 }
 
-uint32_t WritableMappedBlockStream::getLength() const {
+uint32_t WritableMappedBlockStream::getLength() {
   return ReadInterface.getLength();
 }
 
 Error WritableMappedBlockStream::writeBytes(uint32_t Offset,
-                                            ArrayRef<uint8_t> Buffer) const {
+                                            ArrayRef<uint8_t> Buffer) {
   // Make sure we aren't trying to write beyond the end of the stream.
   if (Buffer.size() > getStreamLength())
     return make_error<MSFError>(msf_error_code::insufficient_buffer);
@@ -410,6 +408,4 @@
   return Error::success();
 }
 
-Error WritableMappedBlockStream::commit() const {
-  return WriteInterface.commit();
-}
+Error WritableMappedBlockStream::commit() { return WriteInterface.commit(); }
Index: llvm/lib/DebugInfo/MSF/StreamReader.cpp
===================================================================
--- llvm/lib/DebugInfo/MSF/StreamReader.cpp
+++ /dev/null
@@ -1,92 +0,0 @@
-//===- StreamReader.cpp - Reads bytes and objects from a stream -----------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-
-#include "llvm/DebugInfo/MSF/MSFError.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
-
-using namespace llvm;
-using namespace llvm::msf;
-
-StreamReader::StreamReader(ReadableStreamRef S) : Stream(S), Offset(0) {}
-
-Error StreamReader::readLongestContiguousChunk(ArrayRef<uint8_t> &Buffer) {
-  if (auto EC = Stream.readLongestContiguousChunk(Offset, Buffer))
-    return EC;
-  Offset += Buffer.size();
-  return Error::success();
-}
-
-Error StreamReader::readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size) {
-  if (auto EC = Stream.readBytes(Offset, Size, Buffer))
-    return EC;
-  Offset += Size;
-  return Error::success();
-}
-
-Error StreamReader::readZeroString(StringRef &Dest) {
-  uint32_t Length = 0;
-  // First compute the length of the string by reading 1 byte at a time.
-  uint32_t OriginalOffset = getOffset();
-  const char *C;
-  do {
-    if (auto EC = readObject(C))
-      return EC;
-    if (*C != '\0')
-      ++Length;
-  } while (*C != '\0');
-  // Now go back and request a reference for that many bytes.
-  uint32_t NewOffset = getOffset();
-  setOffset(OriginalOffset);
-
-  ArrayRef<uint8_t> Data;
-  if (auto EC = readBytes(Data, Length))
-    return EC;
-  Dest = StringRef(reinterpret_cast<const char *>(Data.begin()), Data.size());
-
-  // Now set the offset back to where it was after we calculated the length.
-  setOffset(NewOffset);
-  return Error::success();
-}
-
-Error StreamReader::readFixedString(StringRef &Dest, uint32_t Length) {
-  ArrayRef<uint8_t> Bytes;
-  if (auto EC = readBytes(Bytes, Length))
-    return EC;
-  Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size());
-  return Error::success();
-}
-
-Error StreamReader::readStreamRef(ReadableStreamRef &Ref) {
-  return readStreamRef(Ref, bytesRemaining());
-}
-
-Error StreamReader::readStreamRef(ReadableStreamRef &Ref, uint32_t Length) {
-  if (bytesRemaining() < Length)
-    return make_error<MSFError>(msf_error_code::insufficient_buffer);
-  Ref = Stream.slice(Offset, Length);
-  Offset += Length;
-  return Error::success();
-}
-
-Error StreamReader::skip(uint32_t Amount) {
-  if (Amount > bytesRemaining())
-    return make_error<MSFError>(msf_error_code::insufficient_buffer);
-  Offset += Amount;
-  return Error::success();
-}
-
-uint8_t StreamReader::peek() const {
-  ArrayRef<uint8_t> Buffer;
-  auto EC = Stream.readBytes(Offset, 1, Buffer);
-  assert(!EC && "Cannot peek an empty buffer!");
-  llvm::consumeError(std::move(EC));
-  return Buffer[0];
-}
Index: llvm/lib/DebugInfo/MSF/StreamWriter.cpp
===================================================================
--- llvm/lib/DebugInfo/MSF/StreamWriter.cpp
+++ /dev/null
@@ -1,70 +0,0 @@
-//===- StreamWrite.cpp - Writes bytes and objects to a stream -------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
-
-#include "llvm/DebugInfo/MSF/MSFError.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
-
-using namespace llvm;
-using namespace llvm::msf;
-
-StreamWriter::StreamWriter(WritableStreamRef S) : Stream(S), Offset(0) {}
-
-Error StreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
-  if (auto EC = Stream.writeBytes(Offset, Buffer))
-    return EC;
-  Offset += Buffer.size();
-  return Error::success();
-}
-
-Error StreamWriter::writeZeroString(StringRef Str) {
-  if (auto EC = writeFixedString(Str))
-    return EC;
-  if (auto EC = writeObject('\0'))
-    return EC;
-
-  return Error::success();
-}
-
-Error StreamWriter::writeFixedString(StringRef Str) {
-  ArrayRef<uint8_t> Bytes(Str.bytes_begin(), Str.bytes_end());
-  if (auto EC = Stream.writeBytes(Offset, Bytes))
-    return EC;
-
-  Offset += Str.size();
-  return Error::success();
-}
-
-Error StreamWriter::writeStreamRef(ReadableStreamRef Ref) {
-  if (auto EC = writeStreamRef(Ref, Ref.getLength()))
-    return EC;
-  // Don't increment Offset here, it is done by the overloaded call to
-  // writeStreamRef.
-  return Error::success();
-}
-
-Error StreamWriter::writeStreamRef(ReadableStreamRef Ref, uint32_t Length) {
-  Ref = Ref.slice(0, Length);
-
-  StreamReader SrcReader(Ref);
-  // This is a bit tricky.  If we just call readBytes, we are requiring that it
-  // return us the entire stream as a contiguous buffer.  For large streams this
-  // will allocate a huge amount of space from the pool.  Instead, iterate over
-  // each contiguous chunk until we've consumed the entire stream.
-  while (SrcReader.bytesRemaining() > 0) {
-    ArrayRef<uint8_t> Chunk;
-    if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
-      return EC;
-    if (auto EC = writeBytes(Chunk))
-      return EC;
-  }
-  return Error::success();
-}
Index: llvm/lib/DebugInfo/PDB/Native/DbiStream.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/DbiStream.cpp
+++ llvm/lib/DebugInfo/PDB/Native/DbiStream.cpp
@@ -10,8 +10,6 @@
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/ISectionContribVisitor.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
 #include "llvm/DebugInfo/PDB/Native/ModInfo.h"
@@ -21,6 +19,8 @@
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
 #include "llvm/Object/COFF.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
 #include <cstddef>
@@ -34,7 +34,7 @@
 
 template <typename ContribType>
 static Error loadSectionContribs(FixedStreamArray<ContribType> &Output,
-                                 StreamReader &Reader) {
+                                 BinaryStreamReader &Reader) {
   if (Reader.bytesRemaining() % sizeof(ContribType) != 0)
     return make_error<RawError>(
         raw_error_code::corrupt_file,
@@ -52,7 +52,7 @@
 DbiStream::~DbiStream() = default;
 
 Error DbiStream::reload() {
-  StreamReader Reader(*Stream);
+  BinaryStreamReader Reader(*Stream, little);
 
   if (Stream->getLength() < sizeof(DbiStreamHeader))
     return make_error<RawError>(raw_error_code::corrupt_file,
@@ -145,7 +145,7 @@
                                 "Found unexpected bytes in DBI Stream.");
 
   if (ECSubstream.getLength() > 0) {
-    StreamReader ECReader(ECSubstream);
+    BinaryStreamReader ECReader(ECSubstream, little);
     if (auto EC = ECNames.load(ECReader))
       return EC;
   }
@@ -207,16 +207,16 @@
   return static_cast<PDB_Machine>(Machine);
 }
 
-msf::FixedStreamArray<object::coff_section> DbiStream::getSectionHeaders() {
+FixedStreamArray<object::coff_section> DbiStream::getSectionHeaders() {
   return SectionHeaders;
 }
 
-msf::FixedStreamArray<object::FpoData> DbiStream::getFpoRecords() {
+FixedStreamArray<object::FpoData> DbiStream::getFpoRecords() {
   return FpoRecords;
 }
 
 ArrayRef<ModuleInfoEx> DbiStream::modules() const { return ModuleInfos; }
-msf::FixedStreamArray<SecMapEntry> DbiStream::getSectionMap() const {
+FixedStreamArray<SecMapEntry> DbiStream::getSectionMap() const {
   return SectionMap;
 }
 
@@ -235,8 +235,8 @@
   if (SecContrSubstream.getLength() == 0)
     return Error::success();
 
-  StreamReader SCReader(SecContrSubstream);
-  if (auto EC = SCReader.readEnum(SectionContribVersion, llvm::support::little))
+  BinaryStreamReader SCReader(SecContrSubstream, little);
+  if (auto EC = SCReader.readEnum(SectionContribVersion))
     return EC;
 
   if (SectionContribVersion == DbiSecContribVer60)
@@ -254,7 +254,7 @@
 
   // Since each ModInfo in the stream is a variable length, we have to iterate
   // them to know how many there actually are.
-  StreamReader Reader(ModInfoSubstream);
+  BinaryStreamReader Reader(ModInfoSubstream, little);
 
   VarStreamArray<ModInfo> ModInfoArray;
   if (auto EC = Reader.readArray(ModInfoArray, ModInfoSubstream.getLength()))
@@ -284,7 +284,7 @@
                                 "Corrupted section header stream.");
 
   size_t NumSections = StreamLen / sizeof(object::coff_section);
-  msf::StreamReader Reader(*SHS);
+  BinaryStreamReader Reader(*SHS, little);
   if (auto EC = Reader.readArray(SectionHeaders, NumSections))
     return make_error<RawError>(raw_error_code::corrupt_file,
                                 "Could not read a bitmap.");
@@ -316,7 +316,7 @@
                                 "Corrupted New FPO stream.");
 
   size_t NumRecords = StreamLen / sizeof(object::FpoData);
-  msf::StreamReader Reader(*FS);
+  BinaryStreamReader Reader(*FS, little);
   if (auto EC = Reader.readArray(FpoRecords, NumRecords))
     return make_error<RawError>(raw_error_code::corrupt_file,
                                 "Corrupted New FPO stream.");
@@ -328,7 +328,7 @@
   if (SecMapSubstream.getLength() == 0)
     return Error::success();
 
-  StreamReader SMReader(SecMapSubstream);
+  BinaryStreamReader SMReader(SecMapSubstream, little);
   const SecMapHeader *Header;
   if (auto EC = SMReader.readObject(Header))
     return EC;
@@ -342,7 +342,7 @@
     return Error::success();
 
   const FileInfoSubstreamHeader *FH;
-  StreamReader FISR(FileInfoSubstream);
+  BinaryStreamReader FISR(FileInfoSubstream, little);
   if (auto EC = FISR.readObject(FH))
     return EC;
 
@@ -411,7 +411,7 @@
 }
 
 Expected<StringRef> DbiStream::getFileNameForIndex(uint32_t Index) const {
-  StreamReader Names(NamesBuffer);
+  BinaryStreamReader Names(NamesBuffer, little);
   if (Index >= FileNameOffsets.size())
     return make_error<RawError>(raw_error_code::index_out_of_bounds);
 
Index: llvm/lib/DebugInfo/PDB/Native/DbiStreamBuilder.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/DbiStreamBuilder.cpp
+++ llvm/lib/DebugInfo/PDB/Native/DbiStreamBuilder.cpp
@@ -12,10 +12,10 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/Object/COFF.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/COFF.h"
 
 using namespace llvm;
@@ -153,9 +153,9 @@
   uint32_t Size = calculateModiSubstreamSize();
   auto Data = Allocator.Allocate<uint8_t>(Size);
 
-  ModInfoBuffer = MutableByteStream(MutableArrayRef<uint8_t>(Data, Size));
+  ModInfoBuffer = MutableBinaryByteStream(MutableArrayRef<uint8_t>(Data, Size));
 
-  StreamWriter ModiWriter(ModInfoBuffer);
+  BinaryStreamWriter ModiWriter(ModInfoBuffer, llvm::support::little);
   for (const auto &M : ModuleInfoList) {
     ModuleInfoHeader Layout = {};
     Layout.ModDiStream = kInvalidStreamIndex;
@@ -179,29 +179,26 @@
   auto Data = Allocator.Allocate<uint8_t>(Size);
   uint32_t NamesOffset = Size - NameSize;
 
-  FileInfoBuffer = MutableByteStream(MutableArrayRef<uint8_t>(Data, Size));
+  FileInfoBuffer =
+      MutableBinaryByteStream(MutableArrayRef<uint8_t>(Data, Size));
 
-  WritableStreamRef MetadataBuffer =
-      WritableStreamRef(FileInfoBuffer).keep_front(NamesOffset);
-  StreamWriter MetadataWriter(MetadataBuffer);
+  WritableBinaryStreamRef MetadataBuffer =
+      WritableBinaryStreamRef(FileInfoBuffer).keep_front(NamesOffset);
+  BinaryStreamWriter MetadataWriter(MetadataBuffer, llvm::support::little);
 
   uint16_t ModiCount = std::min<uint32_t>(UINT16_MAX, ModuleInfos.size());
   uint16_t FileCount = std::min<uint32_t>(UINT16_MAX, SourceFileNames.size());
-  if (auto EC = MetadataWriter.writeInteger(
-          ModiCount, llvm::support::little)) // NumModules
+  if (auto EC = MetadataWriter.writeInteger(ModiCount)) // NumModules
     return EC;
-  if (auto EC = MetadataWriter.writeInteger(
-          FileCount, llvm::support::little)) // NumSourceFiles
+  if (auto EC = MetadataWriter.writeInteger(FileCount)) // NumSourceFiles
     return EC;
   for (uint16_t I = 0; I < ModiCount; ++I) {
-    if (auto EC = MetadataWriter.writeInteger(
-            I, llvm::support::little)) // Mod Indices
+    if (auto EC = MetadataWriter.writeInteger(I)) // Mod Indices
       return EC;
   }
   for (const auto MI : ModuleInfoList) {
     FileCount = static_cast<uint16_t>(MI->SourceFiles.size());
-    if (auto EC = MetadataWriter.writeInteger(
-            FileCount, llvm::support::little)) // Mod File Counts
+    if (auto EC = MetadataWriter.writeInteger(FileCount)) // Mod File Counts
       return EC;
   }
 
@@ -209,8 +206,8 @@
   // A side effect of this is that this will actually compute the various
   // file name offsets, so we can then go back and write the FileNameOffsets
   // array to the other substream.
-  NamesBuffer = WritableStreamRef(FileInfoBuffer).drop_front(NamesOffset);
-  StreamWriter NameBufferWriter(NamesBuffer);
+  NamesBuffer = WritableBinaryStreamRef(FileInfoBuffer).drop_front(NamesOffset);
+  BinaryStreamWriter NameBufferWriter(NamesBuffer, llvm::support::little);
   for (auto &Name : SourceFileNames) {
     Name.second = NameBufferWriter.getOffset();
     if (auto EC = NameBufferWriter.writeZeroString(Name.getKey()))
@@ -223,8 +220,7 @@
       if (Result == SourceFileNames.end())
         return make_error<RawError>(raw_error_code::no_entry,
                                     "The source file was not found.");
-      if (auto EC = MetadataWriter.writeInteger(Result->second,
-                                                llvm::support::little))
+      if (auto EC = MetadataWriter.writeInteger(Result->second))
         return EC;
     }
   }
@@ -363,14 +359,14 @@
 }
 
 Error DbiStreamBuilder::commit(const msf::MSFLayout &Layout,
-                               const msf::WritableStream &Buffer) {
+                               WritableBinaryStreamRef Buffer) {
   if (auto EC = finalize())
     return EC;
 
   auto InfoS =
       WritableMappedBlockStream::createIndexedStream(Layout, Buffer, StreamDBI);
 
-  StreamWriter Writer(*InfoS);
+  BinaryStreamWriter Writer(*InfoS, llvm::support::little);
   if (auto EC = Writer.writeObject(*Header))
     return EC;
 
@@ -378,7 +374,7 @@
     return EC;
 
   if (!SectionContribs.empty()) {
-    if (auto EC = Writer.writeEnum(DbiSecContribVer60, llvm::support::little))
+    if (auto EC = Writer.writeEnum(DbiSecContribVer60))
       return EC;
     if (auto EC = Writer.writeArray(SectionContribs))
       return EC;
@@ -397,8 +393,7 @@
     return EC;
 
   for (auto &Stream : DbgStreams)
-    if (auto EC =
-            Writer.writeInteger(Stream.StreamNumber, llvm::support::little))
+    if (auto EC = Writer.writeInteger(Stream.StreamNumber))
       return EC;
 
   for (auto &Stream : DbgStreams) {
@@ -406,7 +401,7 @@
       continue;
     auto WritableStream = WritableMappedBlockStream::createIndexedStream(
         Layout, Buffer, Stream.StreamNumber);
-    StreamWriter DbgStreamWriter(*WritableStream);
+    BinaryStreamWriter DbgStreamWriter(*WritableStream, llvm::support::little);
     if (auto EC = DbgStreamWriter.writeArray(Stream.Data))
       return EC;
   }
Index: llvm/lib/DebugInfo/PDB/Native/GSI.h
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/GSI.h
+++ llvm/lib/DebugInfo/PDB/Native/GSI.h
@@ -25,17 +25,15 @@
 #ifndef LLVM_LIB_DEBUGINFO_PDB_RAW_GSI_H
 #define LLVM_LIB_DEBUGINFO_PDB_RAW_GSI_H
 
-#include "llvm/DebugInfo/MSF/StreamArray.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 
+#include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
 
-namespace msf {
-class StreamReader;
-}
+class BinaryStreamReader;
 
 namespace pdb {
 
@@ -56,14 +54,14 @@
   support::ulittle32_t NumBuckets;
 };
 
-Error readGSIHashBuckets(
-    msf::FixedStreamArray<support::ulittle32_t> &HashBuckets,
-    const GSIHashHeader *HashHdr, msf::StreamReader &Reader);
+Error readGSIHashBuckets(FixedStreamArray<support::ulittle32_t> &HashBuckets,
+                         const GSIHashHeader *HashHdr,
+                         BinaryStreamReader &Reader);
 Error readGSIHashHeader(const GSIHashHeader *&HashHdr,
-                        msf::StreamReader &Reader);
-Error readGSIHashRecords(msf::FixedStreamArray<PSHashRecord> &HashRecords,
+                        BinaryStreamReader &Reader);
+Error readGSIHashRecords(FixedStreamArray<PSHashRecord> &HashRecords,
                          const GSIHashHeader *HashHdr,
-                         msf::StreamReader &Reader);
+                         BinaryStreamReader &Reader);
 }
 }
 
Index: llvm/lib/DebugInfo/PDB/Native/GSI.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/GSI.cpp
+++ llvm/lib/DebugInfo/PDB/Native/GSI.cpp
@@ -9,11 +9,11 @@
 
 #include "GSI.h"
 
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
@@ -28,9 +28,9 @@
   return Error::success();
 }
 
-Error readGSIHashBuckets(
-    msf::FixedStreamArray<support::ulittle32_t> &HashBuckets,
-    const GSIHashHeader *HashHdr, msf::StreamReader &Reader) {
+Error readGSIHashBuckets(FixedStreamArray<support::ulittle32_t> &HashBuckets,
+                         const GSIHashHeader *HashHdr,
+                         BinaryStreamReader &Reader) {
   if (auto EC = checkHashHdrVersion(HashHdr))
     return EC;
 
@@ -57,7 +57,7 @@
 }
 
 Error readGSIHashHeader(const GSIHashHeader *&HashHdr,
-                        msf::StreamReader &Reader) {
+                        BinaryStreamReader &Reader) {
   if (Reader.readObject(HashHdr))
     return make_error<RawError>(raw_error_code::corrupt_file,
                                 "Stream does not contain a GSIHashHeader.");
@@ -70,9 +70,9 @@
   return Error::success();
 }
 
-Error readGSIHashRecords(msf::FixedStreamArray<PSHashRecord> &HashRecords,
+Error readGSIHashRecords(FixedStreamArray<PSHashRecord> &HashRecords,
                          const GSIHashHeader *HashHdr,
-                         msf::StreamReader &Reader) {
+                         BinaryStreamReader &Reader) {
   if (auto EC = checkHashHdrVersion(HashHdr))
     return EC;
 
Index: llvm/lib/DebugInfo/PDB/Native/GlobalsStream.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/GlobalsStream.cpp
+++ llvm/lib/DebugInfo/PDB/Native/GlobalsStream.cpp
@@ -9,7 +9,7 @@
 
 #include "llvm/DebugInfo/PDB/Native/GlobalsStream.h"
 #include "GSI.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
 
@@ -23,7 +23,7 @@
 GlobalsStream::~GlobalsStream() = default;
 
 Error GlobalsStream::reload() {
-  StreamReader Reader(*Stream);
+  BinaryStreamReader Reader(*Stream, llvm::support::little);
 
   const GSIHashHeader *HashHdr;
   if (auto EC = readGSIHashHeader(HashHdr, Reader))
Index: llvm/lib/DebugInfo/PDB/Native/HashTable.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/HashTable.cpp
+++ llvm/lib/DebugInfo/PDB/Native/HashTable.cpp
@@ -22,7 +22,7 @@
 
 HashTable::HashTable(uint32_t Capacity) { Buckets.resize(Capacity); }
 
-Error HashTable::load(msf::StreamReader &Stream) {
+Error HashTable::load(BinaryStreamReader &Stream) {
   const Header *H;
   if (auto EC = Stream.readObject(H))
     return EC;
@@ -48,9 +48,9 @@
                                 "Present bit vector interesects deleted!");
 
   for (uint32_t P : Present) {
-    if (auto EC = Stream.readInteger(Buckets[P].first, llvm::support::little))
+    if (auto EC = Stream.readInteger(Buckets[P].first))
       return EC;
-    if (auto EC = Stream.readInteger(Buckets[P].second, llvm::support::little))
+    if (auto EC = Stream.readInteger(Buckets[P].second))
       return EC;
   }
 
@@ -77,7 +77,7 @@
   return Size;
 }
 
-Error HashTable::commit(msf::StreamWriter &Writer) const {
+Error HashTable::commit(BinaryStreamWriter &Writer) const {
   Header H;
   H.Size = size();
   H.Capacity = capacity();
@@ -91,9 +91,9 @@
     return EC;
 
   for (const auto &Entry : *this) {
-    if (auto EC = Writer.writeInteger(Entry.first, llvm::support::little))
+    if (auto EC = Writer.writeInteger(Entry.first))
       return EC;
-    if (auto EC = Writer.writeInteger(Entry.second, llvm::support::little))
+    if (auto EC = Writer.writeInteger(Entry.second))
       return EC;
   }
   return Error::success();
@@ -209,10 +209,10 @@
   assert(size() == S);
 }
 
-Error HashTable::readSparseBitVector(msf::StreamReader &Stream,
+Error HashTable::readSparseBitVector(BinaryStreamReader &Stream,
                                      SparseBitVector<> &V) {
   uint32_t NumWords;
-  if (auto EC = Stream.readInteger(NumWords, llvm::support::little))
+  if (auto EC = Stream.readInteger(NumWords))
     return joinErrors(
         std::move(EC),
         make_error<RawError>(raw_error_code::corrupt_file,
@@ -220,7 +220,7 @@
 
   for (uint32_t I = 0; I != NumWords; ++I) {
     uint32_t Word;
-    if (auto EC = Stream.readInteger(Word, llvm::support::little))
+    if (auto EC = Stream.readInteger(Word))
       return joinErrors(std::move(EC),
                         make_error<RawError>(raw_error_code::corrupt_file,
                                              "Expected hash table word"));
@@ -231,11 +231,11 @@
   return Error::success();
 }
 
-Error HashTable::writeSparseBitVector(msf::StreamWriter &Writer,
+Error HashTable::writeSparseBitVector(BinaryStreamWriter &Writer,
                                       SparseBitVector<> &Vec) {
   int ReqBits = Vec.find_last() + 1;
   uint32_t NumWords = alignTo(ReqBits, sizeof(uint32_t)) / sizeof(uint32_t);
-  if (auto EC = Writer.writeInteger(NumWords, llvm::support::little))
+  if (auto EC = Writer.writeInteger(NumWords))
     return joinErrors(
         std::move(EC),
         make_error<RawError>(raw_error_code::corrupt_file,
@@ -248,7 +248,7 @@
       if (Vec.test(Idx))
         Word |= (1 << WordIdx);
     }
-    if (auto EC = Writer.writeInteger(Word, llvm::support::little))
+    if (auto EC = Writer.writeInteger(Word))
       return joinErrors(std::move(EC), make_error<RawError>(
                                            raw_error_code::corrupt_file,
                                            "Could not write linear map word"));
Index: llvm/lib/DebugInfo/PDB/Native/InfoStream.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/InfoStream.cpp
+++ llvm/lib/DebugInfo/PDB/Native/InfoStream.cpp
@@ -10,12 +10,12 @@
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -26,7 +26,7 @@
     : Stream(std::move(Stream)) {}
 
 Error InfoStream::reload() {
-  StreamReader Reader(*Stream);
+  BinaryStreamReader Reader(*Stream, llvm::support::little);
 
   const InfoStreamHeader *H;
   if (auto EC = Reader.readObject(H))
Index: llvm/lib/DebugInfo/PDB/Native/InfoStreamBuilder.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/InfoStreamBuilder.cpp
+++ llvm/lib/DebugInfo/PDB/Native/InfoStreamBuilder.cpp
@@ -11,12 +11,12 @@
 
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
 #include "llvm/DebugInfo/PDB/Native/NamedStreamMap.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFileBuilder.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -44,10 +44,10 @@
 }
 
 Error InfoStreamBuilder::commit(const msf::MSFLayout &Layout,
-                                const msf::WritableStream &Buffer) const {
+                                WritableBinaryStreamRef Buffer) const {
   auto InfoS =
       WritableMappedBlockStream::createIndexedStream(Layout, Buffer, StreamPDB);
-  StreamWriter Writer(*InfoS);
+  BinaryStreamWriter Writer(*InfoS, llvm::support::little);
 
   InfoStreamHeader H;
   H.Age = Age;
Index: llvm/lib/DebugInfo/PDB/Native/ModInfo.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/ModInfo.cpp
+++ llvm/lib/DebugInfo/PDB/Native/ModInfo.cpp
@@ -8,15 +8,15 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/PDB/Native/ModInfo.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MathExtras.h"
 #include <cstdint>
 
 using namespace llvm;
-using namespace llvm::msf;
 using namespace llvm::pdb;
 using namespace llvm::support;
 
@@ -26,8 +26,8 @@
 
 ModInfo::~ModInfo() = default;
 
-Error ModInfo::initialize(ReadableStreamRef Stream, ModInfo &Info) {
-  StreamReader Reader(Stream);
+Error ModInfo::initialize(BinaryStreamRef Stream, ModInfo &Info) {
+  BinaryStreamReader Reader(Stream, little);
   if (auto EC = Reader.readObject(Info.Layout))
     return EC;
 
Index: llvm/lib/DebugInfo/PDB/Native/ModStream.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/ModStream.cpp
+++ llvm/lib/DebugInfo/PDB/Native/ModStream.cpp
@@ -10,12 +10,12 @@
 #include "llvm/DebugInfo/PDB/Native/ModStream.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
 #include "llvm/DebugInfo/PDB/Native/ModInfo.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
 #include <cstdint>
@@ -31,7 +31,7 @@
 ModStream::~ModStream() = default;
 
 Error ModStream::reload() {
-  StreamReader Reader(*Stream);
+  BinaryStreamReader Reader(*Stream, llvm::support::little);
 
   uint32_t SymbolSize = Mod.getSymbolDebugInfoByteSize();
   uint32_t C11Size = Mod.getLineInfoByteSize();
@@ -41,9 +41,9 @@
     return make_error<RawError>(raw_error_code::corrupt_file,
                                 "Module has both C11 and C13 line info");
 
-  ReadableStreamRef S;
+  BinaryStreamRef S;
 
-  if (auto EC = Reader.readInteger(Signature, llvm::support::little))
+  if (auto EC = Reader.readInteger(Signature))
     return EC;
   if (auto EC = Reader.readArray(SymbolsSubstream, SymbolSize - 4))
     return EC;
@@ -53,12 +53,12 @@
   if (auto EC = Reader.readStreamRef(C13LinesSubstream, C13Size))
     return EC;
 
-  StreamReader LineReader(C13LinesSubstream);
+  BinaryStreamReader LineReader(C13LinesSubstream, llvm::support::little);
   if (auto EC = LineReader.readArray(LineInfo, LineReader.bytesRemaining()))
     return EC;
 
   uint32_t GlobalRefsSize;
-  if (auto EC = Reader.readInteger(GlobalRefsSize, llvm::support::little))
+  if (auto EC = Reader.readInteger(GlobalRefsSize))
     return EC;
   if (auto EC = Reader.readStreamRef(GlobalRefsSubstream, GlobalRefsSize))
     return EC;
Index: llvm/lib/DebugInfo/PDB/Native/NamedStreamMap.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/NamedStreamMap.cpp
+++ llvm/lib/DebugInfo/PDB/Native/NamedStreamMap.cpp
@@ -13,31 +13,30 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/HashTable.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
 #include <cstdint>
 
 using namespace llvm;
-using namespace llvm::msf;
 using namespace llvm::pdb;
 
 NamedStreamMap::NamedStreamMap() = default;
 
-Error NamedStreamMap::load(StreamReader &Stream) {
+Error NamedStreamMap::load(BinaryStreamReader &Stream) {
   Mapping.clear();
   FinalizedHashTable.clear();
   FinalizedInfo.reset();
 
   uint32_t StringBufferSize;
-  if (auto EC = Stream.readInteger(StringBufferSize, llvm::support::little))
+  if (auto EC = Stream.readInteger(StringBufferSize))
     return joinErrors(std::move(EC),
                       make_error<RawError>(raw_error_code::corrupt_file,
                                            "Expected string buffer size"));
 
-  msf::ReadableStreamRef StringsBuffer;
+  BinaryStreamRef StringsBuffer;
   if (auto EC = Stream.readStreamRef(StringsBuffer, StringBufferSize))
     return EC;
 
@@ -51,7 +50,7 @@
     std::tie(NameOffset, NameIndex) = Entry;
 
     // Compute the offset of the start of the string relative to the stream.
-    msf::StreamReader NameReader(StringsBuffer);
+    BinaryStreamReader NameReader(StringsBuffer, llvm::support::little);
     NameReader.setOffset(NameOffset);
     // Pump out our c-string from the stream.
     StringRef Str;
@@ -67,12 +66,11 @@
   return Error::success();
 }
 
-Error NamedStreamMap::commit(msf::StreamWriter &Writer) const {
+Error NamedStreamMap::commit(BinaryStreamWriter &Writer) const {
   assert(FinalizedInfo.hasValue());
 
   // The first field is the number of bytes of string data.
-  if (auto EC = Writer.writeInteger(FinalizedInfo->StringDataBytes,
-                                    llvm::support::little))
+  if (auto EC = Writer.writeInteger(FinalizedInfo->StringDataBytes))
     return EC;
 
   // Now all of the string data itself.
Index: llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
+++ llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
@@ -10,7 +10,6 @@
 #include "llvm/DebugInfo/PDB/Native/NativeSession.h"
 
 #include "llvm/ADT/STLExtras.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 #include "llvm/DebugInfo/PDB/GenericError.h"
 #include "llvm/DebugInfo/PDB/IPDBEnumChildren.h"
 #include "llvm/DebugInfo/PDB/IPDBSourceFile.h"
@@ -19,6 +18,7 @@
 #include "llvm/DebugInfo/PDB/PDBSymbolCompiland.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolExe.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/MemoryBuffer.h"
Index: llvm/lib/DebugInfo/PDB/Native/PDBFile.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/PDBFile.cpp
+++ llvm/lib/DebugInfo/PDB/Native/PDBFile.cpp
@@ -12,9 +12,6 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/DebugInfo/MSF/MSFCommon.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/DebugInfo/PDB/Native/GlobalsStream.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
@@ -23,6 +20,9 @@
 #include "llvm/DebugInfo/PDB/Native/StringTable.h"
 #include "llvm/DebugInfo/PDB/Native/SymbolStream.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStream.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Path.h"
@@ -39,7 +39,7 @@
 typedef FixedStreamArray<support::ulittle32_t> ulittle_array;
 } // end anonymous namespace
 
-PDBFile::PDBFile(StringRef Path, std::unique_ptr<ReadableStream> PdbFileBuffer,
+PDBFile::PDBFile(StringRef Path, std::unique_ptr<BinaryStream> PdbFileBuffer,
                  BumpPtrAllocator &Allocator)
     : FilePath(Path), Allocator(Allocator), Buffer(std::move(PdbFileBuffer)) {}
 
@@ -113,7 +113,7 @@
 }
 
 Error PDBFile::parseFileHeaders() {
-  StreamReader Reader(*Buffer);
+  BinaryStreamReader Reader(*Buffer, llvm::support::little);
 
   // Initialize SB.
   const msf::SuperBlock *SB = nullptr;
@@ -147,7 +147,7 @@
   // See the function fpmPn() for more information:
   // https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/msf/msf.cpp#L489
   auto FpmStream = MappedBlockStream::createFpmStream(ContainerLayout, *Buffer);
-  StreamReader FpmReader(*FpmStream);
+  BinaryStreamReader FpmReader(*FpmStream, llvm::support::little);
   ArrayRef<uint8_t> FpmBytes;
   if (auto EC = FpmReader.readBytes(FpmBytes,
                                     msf::getFullFpmByteSize(ContainerLayout)))
@@ -185,8 +185,8 @@
   // subclass of IPDBStreamData which only accesses the fields that have already
   // been parsed, we can avoid this and reuse MappedBlockStream.
   auto DS = MappedBlockStream::createDirectoryStream(ContainerLayout, *Buffer);
-  StreamReader Reader(*DS);
-  if (auto EC = Reader.readInteger(NumStreams, llvm::support::little))
+  BinaryStreamReader Reader(*DS, llvm::support::little);
+  if (auto EC = Reader.readInteger(NumStreams))
     return EC;
 
   if (auto EC = Reader.readArray(ContainerLayout.StreamSizes, NumStreams))
@@ -350,7 +350,7 @@
     if (!NS)
       return NS.takeError();
 
-    StreamReader Reader(**NS);
+    BinaryStreamReader Reader(**NS, llvm::support::little);
     auto N = llvm::make_unique<StringTable>();
     if (auto EC = N->load(Reader))
       return std::move(EC);
@@ -403,7 +403,7 @@
 /// contain the stream returned by createIndexedStream().
 Expected<std::unique_ptr<MappedBlockStream>>
 PDBFile::safelyCreateIndexedStream(const MSFLayout &Layout,
-                                   const ReadableStream &MsfData,
+                                   BinaryStreamRef MsfData,
                                    uint32_t StreamIndex) const {
   if (StreamIndex >= getNumStreams())
     return make_error<RawError>(raw_error_code::no_stream);
Index: llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
+++ llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
@@ -12,8 +12,6 @@
 #include "llvm/ADT/BitVector.h"
 
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
-#include "llvm/DebugInfo/MSF/StreamInterface.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/GenericError.h"
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/DebugInfo/PDB/Native/DbiStreamBuilder.h"
@@ -23,6 +21,8 @@
 #include "llvm/DebugInfo/PDB/Native/StringTableBuilder.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStream.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStreamBuilder.h"
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -119,7 +119,7 @@
     return llvm::make_error<pdb::GenericError>(generic_error_code::invalid_path,
                                                Filename);
   FileBufferByteStream Buffer(std::move(*OutFileOrError));
-  StreamWriter Writer(Buffer);
+  BinaryStreamWriter Writer(Buffer, llvm::support::little);
 
   if (auto EC = Writer.writeObject(*Layout.SB))
     return EC;
@@ -131,9 +131,8 @@
 
   auto DirStream =
       WritableMappedBlockStream::createDirectoryStream(Layout, Buffer);
-  StreamWriter DW(*DirStream);
-  if (auto EC = DW.writeInteger<uint32_t>(Layout.StreamSizes.size(),
-                                          llvm::support::little))
+  BinaryStreamWriter DW(*DirStream, llvm::support::little);
+  if (auto EC = DW.writeInteger<uint32_t>(Layout.StreamSizes.size()))
     return EC;
 
   if (auto EC = DW.writeArray(Layout.StreamSizes))
@@ -150,7 +149,7 @@
 
   auto NS = WritableMappedBlockStream::createIndexedStream(Layout, Buffer,
                                                            StringTableStreamNo);
-  StreamWriter NSWriter(*NS);
+  BinaryStreamWriter NSWriter(*NS, llvm::support::little);
   if (auto EC = Strings.commit(NSWriter))
     return EC;
 
Index: llvm/lib/DebugInfo/PDB/Native/PublicsStream.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/PublicsStream.cpp
+++ llvm/lib/DebugInfo/PDB/Native/PublicsStream.cpp
@@ -27,10 +27,10 @@
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/SymbolStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
@@ -69,7 +69,7 @@
 // we skip over the hash table which we believe contains information about
 // public symbols.
 Error PublicsStream::reload() {
-  StreamReader Reader(*Stream);
+  BinaryStreamReader Reader(*Stream, llvm::support::little);
 
   // Check stream size.
   if (Reader.bytesRemaining() < sizeof(HeaderInfo) + sizeof(GSIHashHeader))
Index: llvm/lib/DebugInfo/PDB/Native/StringTable.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/StringTable.cpp
+++ llvm/lib/DebugInfo/PDB/Native/StringTable.cpp
@@ -10,20 +10,19 @@
 #include "llvm/DebugInfo/PDB/Native/StringTable.h"
 
 #include "llvm/ADT/ArrayRef.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/Hash.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Endian.h"
 
 using namespace llvm;
-using namespace llvm::msf;
 using namespace llvm::support;
 using namespace llvm::pdb;
 
 StringTable::StringTable() : Signature(0), HashVersion(0), NameCount(0) {}
 
-Error StringTable::load(StreamReader &Stream) {
+Error StringTable::load(BinaryStreamReader &Stream) {
   const StringTableHeader *H;
   if (auto EC = Stream.readObject(H))
     return EC;
@@ -55,7 +54,7 @@
     return make_error<RawError>(raw_error_code::corrupt_file,
                                 "Missing name count");
 
-  if (auto EC = Stream.readInteger(NameCount, llvm::support::little))
+  if (auto EC = Stream.readInteger(NameCount))
     return EC;
   return Error::success();
 }
@@ -68,7 +67,7 @@
   // the starting offset of the string we're looking for.  So just seek into
   // the desired offset and a read a null terminated stream from that offset.
   StringRef Result;
-  StreamReader NameReader(NamesBuffer);
+  BinaryStreamReader NameReader(NamesBuffer, llvm::support::little);
   NameReader.setOffset(ID);
   if (auto EC = NameReader.readZeroString(Result))
     consumeError(std::move(EC));
Index: llvm/lib/DebugInfo/PDB/Native/StringTableBuilder.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/StringTableBuilder.cpp
+++ llvm/lib/DebugInfo/PDB/Native/StringTableBuilder.cpp
@@ -9,9 +9,9 @@
 
 #include "llvm/DebugInfo/PDB/Native/StringTableBuilder.h"
 #include "llvm/ADT/ArrayRef.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/Native/Hash.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Endian.h"
 
 using namespace llvm;
@@ -52,7 +52,7 @@
   return Size;
 }
 
-Error StringTableBuilder::commit(msf::StreamWriter &Writer) const {
+Error StringTableBuilder::commit(BinaryStreamWriter &Writer) const {
   // Write a header
   StringTableHeader H;
   H.Signature = StringTableSignature;
@@ -74,7 +74,7 @@
 
   // Write a hash table.
   uint32_t BucketCount = computeBucketCount(Strings.size());
-  if (auto EC = Writer.writeInteger(BucketCount, llvm::support::little))
+  if (auto EC = Writer.writeInteger(BucketCount))
     return EC;
   std::vector<ulittle32_t> Buckets(BucketCount);
 
@@ -96,8 +96,7 @@
 
   if (auto EC = Writer.writeArray(ArrayRef<ulittle32_t>(Buckets)))
     return EC;
-  if (auto EC = Writer.writeInteger(static_cast<uint32_t>(Strings.size()),
-                                    llvm::support::little))
+  if (auto EC = Writer.writeInteger(static_cast<uint32_t>(Strings.size())))
     return EC;
   return Error::success();
 }
Index: llvm/lib/DebugInfo/PDB/Native/SymbolStream.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/SymbolStream.cpp
+++ llvm/lib/DebugInfo/PDB/Native/SymbolStream.cpp
@@ -12,11 +12,11 @@
 #include "llvm/DebugInfo/CodeView/CodeView.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Endian.h"
 
 using namespace llvm;
@@ -30,7 +30,7 @@
 SymbolStream::~SymbolStream() {}
 
 Error SymbolStream::reload() {
-  StreamReader Reader(*Stream);
+  BinaryStreamReader Reader(*Stream, llvm::support::little);
 
   if (auto EC = Reader.readArray(SymbolRecords, Stream->getLength()))
     return EC;
Index: llvm/lib/DebugInfo/PDB/Native/TpiStream.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/TpiStream.cpp
+++ llvm/lib/DebugInfo/PDB/Native/TpiStream.cpp
@@ -14,13 +14,13 @@
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbackPipeline.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/PDBTypeServerHandler.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/DebugInfo/PDB/Native/TpiHashing.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
@@ -54,7 +54,7 @@
 }
 
 Error TpiStream::reload() {
-  StreamReader Reader(*Stream);
+  BinaryStreamReader Reader(*Stream, llvm::support::little);
 
   if (Reader.bytesRemaining() < sizeof(TpiStreamHeader))
     return make_error<RawError>(raw_error_code::corrupt_file,
@@ -93,7 +93,7 @@
 
     auto HS = MappedBlockStream::createIndexedStream(
         Pdb.getMsfLayout(), Pdb.getMsfBuffer(), Header->HashStreamIndex);
-    StreamReader HSR(*HS);
+    BinaryStreamReader HSR(*HS, llvm::support::little);
 
     uint32_t NumHashValues =
         Header->HashValueBuffer.Length / sizeof(ulittle32_t);
Index: llvm/lib/DebugInfo/PDB/Native/TpiStreamBuilder.cpp
===================================================================
--- llvm/lib/DebugInfo/PDB/Native/TpiStreamBuilder.cpp
+++ llvm/lib/DebugInfo/PDB/Native/TpiStreamBuilder.cpp
@@ -12,17 +12,17 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamArray.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStream.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
@@ -82,7 +82,7 @@
   return Error::success();
 }
 
-uint32_t TpiStreamBuilder::calculateSerializedLength() const {
+uint32_t TpiStreamBuilder::calculateSerializedLength() {
   return sizeof(TpiStreamHeader) + TypeRecordStream.getLength();
 }
 
@@ -113,19 +113,19 @@
   }
   ArrayRef<uint8_t> Bytes(reinterpret_cast<const uint8_t *>(HashBuffer.data()),
                           HashBufferSize);
-  HashValueStream = llvm::make_unique<ByteStream>(Bytes);
+  HashValueStream = llvm::make_unique<BinaryByteStream>(Bytes);
   return Error::success();
 }
 
 Error TpiStreamBuilder::commit(const msf::MSFLayout &Layout,
-                               const msf::WritableStream &Buffer) {
+                               WritableBinaryStreamRef Buffer) {
   if (auto EC = finalize())
     return EC;
 
   auto InfoS =
       WritableMappedBlockStream::createIndexedStream(Layout, Buffer, Idx);
 
-  StreamWriter Writer(*InfoS);
+  BinaryStreamWriter Writer(*InfoS, llvm::support::little);
   if (auto EC = Writer.writeObject(*Header))
     return EC;
 
@@ -136,7 +136,7 @@
   if (HashStreamIndex != kInvalidStreamIndex) {
     auto HVS = WritableMappedBlockStream::createIndexedStream(Layout, Buffer,
                                                               HashStreamIndex);
-    StreamWriter HW(*HVS);
+    BinaryStreamWriter HW(*HVS, llvm::support::little);
     if (auto EC = HW.writeStreamRef(*HashValueStream))
       return EC;
   }
Index: llvm/lib/Support/BinaryStreamReader.cpp
===================================================================
--- /dev/null
+++ llvm/lib/Support/BinaryStreamReader.cpp
@@ -0,0 +1,94 @@
+//===- BinaryStreamReader.cpp - Reads objects from a binary stream --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/BinaryStreamReader.h"
+
+#include "llvm/Support/BinaryStreamRef.h"
+
+using namespace llvm;
+
+BinaryStreamReader::BinaryStreamReader(BinaryStreamRef S,
+                                       llvm::support::endianness Endian)
+    : Stream(S), Offset(0), Endian(Endian) {}
+
+Error BinaryStreamReader::readLongestContiguousChunk(
+    ArrayRef<uint8_t> &Buffer) {
+  if (auto EC = Stream.readLongestContiguousChunk(Offset, Buffer))
+    return EC;
+  Offset += Buffer.size();
+  return Error::success();
+}
+
+Error BinaryStreamReader::readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size) {
+  if (auto EC = Stream.readBytes(Offset, Size, Buffer))
+    return EC;
+  Offset += Size;
+  return Error::success();
+}
+
+Error BinaryStreamReader::readZeroString(StringRef &Dest) {
+  uint32_t Length = 0;
+  // First compute the length of the string by reading 1 byte at a time.
+  uint32_t OriginalOffset = getOffset();
+  const char *C;
+  while (true) {
+    if (auto EC = readObject(C))
+      return EC;
+    if (*C == '\0')
+      break;
+    ++Length;
+  }
+  // Now go back and request a reference for that many bytes.
+  uint32_t NewOffset = getOffset();
+  setOffset(OriginalOffset);
+
+  ArrayRef<uint8_t> Data;
+  if (auto EC = readBytes(Data, Length))
+    return EC;
+  Dest = StringRef(reinterpret_cast<const char *>(Data.begin()), Data.size());
+
+  // Now set the offset back to where it was after we calculated the length.
+  setOffset(NewOffset);
+  return Error::success();
+}
+
+Error BinaryStreamReader::readFixedString(StringRef &Dest, uint32_t Length) {
+  ArrayRef<uint8_t> Bytes;
+  if (auto EC = readBytes(Bytes, Length))
+    return EC;
+  Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size());
+  return Error::success();
+}
+
+Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref) {
+  return readStreamRef(Ref, bytesRemaining());
+}
+
+Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref, uint32_t Length) {
+  if (bytesRemaining() < Length)
+    return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+  Ref = Stream.slice(Offset, Length);
+  Offset += Length;
+  return Error::success();
+}
+
+Error BinaryStreamReader::skip(uint32_t Amount) {
+  if (Amount > bytesRemaining())
+    return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+  Offset += Amount;
+  return Error::success();
+}
+
+uint8_t BinaryStreamReader::peek() const {
+  ArrayRef<uint8_t> Buffer;
+  auto EC = Stream.readBytes(Offset, 1, Buffer);
+  assert(!EC && "Cannot peek an empty buffer!");
+  llvm::consumeError(std::move(EC));
+  return Buffer[0];
+}
Index: llvm/lib/Support/BinaryStreamWriter.cpp
===================================================================
--- /dev/null
+++ llvm/lib/Support/BinaryStreamWriter.cpp
@@ -0,0 +1,71 @@
+//===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/BinaryStreamWriter.h"
+
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
+
+using namespace llvm;
+
+BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef S,
+                                       llvm::support::endianness Endian)
+    : Stream(S), Offset(0), Endian(Endian) {}
+
+Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
+  if (auto EC = Stream.writeBytes(Offset, Buffer))
+    return EC;
+  Offset += Buffer.size();
+  return Error::success();
+}
+
+Error BinaryStreamWriter::writeZeroString(StringRef Str) {
+  if (auto EC = writeFixedString(Str))
+    return EC;
+  if (auto EC = writeObject('\0'))
+    return EC;
+
+  return Error::success();
+}
+
+Error BinaryStreamWriter::writeFixedString(StringRef Str) {
+  ArrayRef<uint8_t> Bytes(Str.bytes_begin(), Str.bytes_end());
+  if (auto EC = Stream.writeBytes(Offset, Bytes))
+    return EC;
+
+  Offset += Str.size();
+  return Error::success();
+}
+
+Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {
+  if (auto EC = writeStreamRef(Ref, Ref.getLength()))
+    return EC;
+  // Don't increment Offset here, it is done by the overloaded call to
+  // writeStreamRef.
+  return Error::success();
+}
+
+Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint32_t Length) {
+  Ref = Ref.slice(0, Length);
+
+  BinaryStreamReader SrcReader(Ref, Endian);
+  // This is a bit tricky.  If we just call readBytes, we are requiring that it
+  // return us the entire stream as a contiguous buffer.  There is no guarantee
+  // this can be satisfied by returning a reference straight from the buffer, as
+  // an implementation may not store all data in a single contiguous buffer.  So
+  // we iterate over each contiguous chunk, writing each one in succession.
+  while (SrcReader.bytesRemaining() > 0) {
+    ArrayRef<uint8_t> Chunk;
+    if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
+      return EC;
+    if (auto EC = writeBytes(Chunk))
+      return EC;
+  }
+  return Error::success();
+}
Index: llvm/lib/Support/CMakeLists.txt
===================================================================
--- llvm/lib/Support/CMakeLists.txt
+++ llvm/lib/Support/CMakeLists.txt
@@ -94,6 +94,8 @@
   SystemUtils.cpp
   TarWriter.cpp
   TargetParser.cpp
+  BinaryStreamReader.cpp
+  BinaryStreamWriter.cpp
   ThreadPool.cpp
   Timer.cpp
   ToolOutputFile.cpp
Index: llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
===================================================================
--- llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
+++ llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
@@ -22,7 +22,6 @@
 #include "llvm/DebugInfo/CodeView/TypeDumpVisitor.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbackPipeline.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/DebugInfo/PDB/Native/EnumTables.h"
 #include "llvm/DebugInfo/PDB/Native/GlobalsStream.h"
@@ -36,6 +35,7 @@
 #include "llvm/DebugInfo/PDB/Native/TpiStream.h"
 #include "llvm/DebugInfo/PDB/PDBExtras.h"
 #include "llvm/Object/COFF.h"
+#include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/FormatVariadic.h"
 
 #include <unordered_map>
@@ -450,7 +450,7 @@
     auto Blocks = File.getMsfLayout().StreamMap[SI];
     P.printList("Blocks", Blocks);
 
-    StreamReader R(*S);
+    BinaryStreamReader R(*S, llvm::support::little);
     ArrayRef<uint8_t> StreamData;
     if (auto EC = R.readBytes(StreamData, S->getLength()))
       return EC;
@@ -745,10 +745,10 @@
           public:
             RecordVisitor(ScopedPrinter &P, PDBFile &F) : P(P), F(F) {}
             Error visitUnknown(ModuleSubstreamKind Kind,
-                               ReadableStreamRef Stream) override {
+                               BinaryStreamRef Stream) override {
               DictScope DD(P, "Unknown");
               ArrayRef<uint8_t> Data;
-              StreamReader R(Stream);
+              BinaryStreamReader R(Stream, llvm::support::little);
               if (auto EC = R.readBytes(Data, R.bytesRemaining())) {
                 return make_error<RawError>(
                     raw_error_code::corrupt_file,
@@ -758,7 +758,7 @@
               return Error::success();
             }
             Error
-            visitFileChecksums(ReadableStreamRef Data,
+            visitFileChecksums(BinaryStreamRef Data,
                                const FileChecksumArray &Checksums) override {
               DictScope DD(P, "FileChecksums");
               for (const auto &C : Checksums) {
@@ -774,7 +774,7 @@
               return Error::success();
             }
 
-            Error visitLines(ReadableStreamRef Data,
+            Error visitLines(BinaryStreamRef Data,
                              const LineSubstreamHeader *Header,
                              const LineInfoArray &Lines) override {
               DictScope DD(P, "Lines");
Index: llvm/tools/llvm-pdbdump/YamlTypeDumper.cpp
===================================================================
--- llvm/tools/llvm-pdbdump/YamlTypeDumper.cpp
+++ llvm/tools/llvm-pdbdump/YamlTypeDumper.cpp
@@ -573,8 +573,8 @@
     assert(IO.outputting());
     codeview::TypeVisitorCallbackPipeline Pipeline;
 
-    msf::ByteStream Data(Obj.Record.Data);
-    msf::StreamReader FieldReader(Data);
+    BinaryByteStream Data(Obj.Record.Data);
+    BinaryStreamReader FieldReader(Data, llvm::support::little);
     codeview::FieldListDeserializer Deserializer(FieldReader);
 
     // For PDB to Yaml, deserialize into a high level record type, then dump
Index: llvm/tools/llvm-pdbdump/llvm-pdbdump.cpp
===================================================================
--- llvm/tools/llvm-pdbdump/llvm-pdbdump.cpp
+++ llvm/tools/llvm-pdbdump/llvm-pdbdump.cpp
@@ -31,7 +31,6 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Config/config.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
 #include "llvm/DebugInfo/PDB/GenericError.h"
 #include "llvm/DebugInfo/PDB/IPDBEnumChildren.h"
Index: llvm/tools/llvm-readobj/COFFDumper.cpp
===================================================================
--- llvm/tools/llvm-readobj/COFFDumper.cpp
+++ llvm/tools/llvm-readobj/COFFDumper.cpp
@@ -35,9 +35,9 @@
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeStreamMerger.h"
 #include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/COFF.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
@@ -56,7 +56,6 @@
 using namespace llvm;
 using namespace llvm::object;
 using namespace llvm::codeview;
-using namespace llvm::msf;
 using namespace llvm::support;
 using namespace llvm::Win64EH;
 
@@ -155,7 +154,7 @@
     Sec = Obj->getCOFFSection(SR);
   }
 
-  uint32_t getRecordOffset(msf::StreamReader Reader) override {
+  uint32_t getRecordOffset(BinaryStreamReader Reader) override {
     ArrayRef<uint8_t> Data;
     if (auto EC = Reader.readLongestContiguousChunk(Data)) {
       llvm::consumeError(std::move(EC));
@@ -841,8 +840,8 @@
     }
     case ModuleSubstreamKind::FrameData: {
       // First four bytes is a relocation against the function.
-      msf::ByteStream S(Contents);
-      msf::StreamReader SR(S);
+      BinaryByteStream S(Contents);
+      BinaryStreamReader SR(S, llvm::support::little);
       const uint32_t *CodePtr;
       error(SR.readObject(CodePtr));
       StringRef LinkageName;
@@ -966,9 +965,9 @@
 
   CVSymbolDumper CVSD(W, TypeDB, std::move(CODD),
                       opts::CodeViewSubsectionBytes);
-  ByteStream Stream(BinaryData);
+  BinaryByteStream Stream(BinaryData);
   CVSymbolArray Symbols;
-  StreamReader Reader(Stream);
+  BinaryStreamReader Reader(Stream, llvm::support::little);
   if (auto EC = Reader.readArray(Symbols, Reader.getLength())) {
     consumeError(std::move(EC));
     W.flush();
@@ -983,8 +982,8 @@
 }
 
 void COFFDumper::printCodeViewFileChecksums(StringRef Subsection) {
-  msf::ByteStream S(Subsection);
-  msf::StreamReader SR(S);
+  BinaryByteStream S(Subsection);
+  BinaryStreamReader SR(S, llvm::support::little);
   while (!SR.empty()) {
     DictScope S(W, "FileChecksum");
     const FileChecksum *FC;
@@ -1012,10 +1011,10 @@
 }
 
 void COFFDumper::printCodeViewInlineeLines(StringRef Subsection) {
-  msf::ByteStream S(Subsection);
-  msf::StreamReader SR(S);
+  BinaryByteStream S(Subsection);
+  BinaryStreamReader SR(S, llvm::support::little);
   uint32_t Signature;
-  error(SR.readInteger(Signature, llvm::support::little));
+  error(SR.readInteger(Signature));
   bool HasExtraFiles = Signature == unsigned(InlineeLinesSignature::ExtraFiles);
 
   while (!SR.empty()) {
@@ -1028,12 +1027,12 @@
 
     if (HasExtraFiles) {
       uint32_t ExtraFileCount;
-      error(SR.readInteger(ExtraFileCount, llvm::support::little));
+      error(SR.readInteger(ExtraFileCount));
       W.printNumber("ExtraFileCount", ExtraFileCount);
       ListScope ExtraFiles(W, "ExtraFiles");
       for (unsigned I = 0; I < ExtraFileCount; ++I) {
         uint32_t FileID;
-        error(SR.readInteger(FileID, llvm::support::little));
+        error(SR.readInteger(FileID));
         printFileNameForOffset("FileID", FileID);
       }
     }
@@ -1078,9 +1077,9 @@
         error(object_error::parse_failed);
       ArrayRef<uint8_t> Bytes(reinterpret_cast<const uint8_t *>(Data.data()),
                               Data.size());
-      ByteStream Stream(Bytes);
+      BinaryByteStream Stream(Bytes);
       CVTypeArray Types;
-      StreamReader Reader(Stream);
+      BinaryStreamReader Reader(Stream, llvm::support::little);
       if (auto EC = Reader.readArray(Types, Reader.getLength())) {
         consumeError(std::move(EC));
         W.flush();
Index: llvm/unittests/DebugInfo/PDB/HashTableTest.cpp
===================================================================
--- llvm/unittests/DebugInfo/PDB/HashTableTest.cpp
+++ llvm/unittests/DebugInfo/PDB/HashTableTest.cpp
@@ -10,10 +10,10 @@
 #include "ErrorChecking.h"
 #include "gtest/gtest.h"
 
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/Native/HashTable.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 
 #include <vector>
 
@@ -147,14 +147,14 @@
   }
 
   std::vector<uint8_t> Buffer(Table.calculateSerializedLength());
-  msf::MutableByteStream Stream(Buffer);
-  msf::StreamWriter Writer(Stream);
+  MutableBinaryByteStream Stream(Buffer);
+  BinaryStreamWriter Writer(Stream, llvm::support::little);
   EXPECT_NO_ERROR(Table.commit(Writer));
   // We should have written precisely the number of bytes we calculated earlier.
   EXPECT_EQ(Buffer.size(), Writer.getOffset());
 
   HashTableInternals Table2;
-  msf::StreamReader Reader(Stream);
+  BinaryStreamReader Reader(Stream, llvm::support::little);
   EXPECT_NO_ERROR(Table2.load(Reader));
   // We should have read precisely the number of bytes we calculated earlier.
   EXPECT_EQ(Buffer.size(), Reader.getOffset());
Index: llvm/unittests/DebugInfo/PDB/MappedBlockStreamTest.cpp
===================================================================
--- llvm/unittests/DebugInfo/PDB/MappedBlockStreamTest.cpp
+++ llvm/unittests/DebugInfo/PDB/MappedBlockStreamTest.cpp
@@ -9,13 +9,13 @@
 
 #include "ErrorChecking.h"
 
-#include "llvm/DebugInfo/MSF/ByteStream.h"
 #include "llvm/DebugInfo/MSF/IMSFFile.h"
-#include "llvm/DebugInfo/MSF/MappedBlockStream.h"
 #include "llvm/DebugInfo/MSF/MSFStreamLayout.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamRef.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
+#include "llvm/DebugInfo/MSF/MappedBlockStream.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 #include "gtest/gtest.h"
 
 #include <unordered_map>
@@ -28,7 +28,7 @@
 static const uint32_t BlocksAry[] = {0, 1, 2, 5, 4, 3, 6, 7, 8, 9};
 static uint8_t DataAry[] = {'A', 'B', 'C', 'F', 'E', 'D', 'G', 'H', 'I', 'J'};
 
-class DiscontiguousStream : public WritableStream {
+class DiscontiguousStream : public WritableBinaryStream {
 public:
   DiscontiguousStream(ArrayRef<uint32_t> Blocks, MutableArrayRef<uint8_t> Data)
       : Blocks(Blocks.begin(), Blocks.end()), Data(Data.begin(), Data.end()) {}
@@ -39,7 +39,7 @@
   Error readBytes(uint32_t Offset, uint32_t Size,
                   ArrayRef<uint8_t> &Buffer) const override {
     if (Offset + Size > Data.size())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
     Buffer = Data.slice(Offset, Size);
     return Error::success();
   }
@@ -47,7 +47,7 @@
   Error readLongestContiguousChunk(uint32_t Offset,
                                    ArrayRef<uint8_t> &Buffer) const override {
     if (Offset >= Data.size())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
     Buffer = Data.drop_front(Offset);
     return Error::success();
   }
@@ -56,7 +56,7 @@
 
   Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> SrcData) const override {
     if (Offset + SrcData.size() > Data.size())
-      return make_error<MSFError>(msf_error_code::insufficient_buffer);
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
     ::memcpy(&Data[Offset], SrcData.data(), SrcData.size());
     return Error::success();
   }
@@ -78,8 +78,8 @@
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
 
-  StreamReader R(*S);
-  ReadableStreamRef SR;
+  BinaryStreamReader R(*S, llvm::support::little);
+  BinaryStreamRef SR;
   EXPECT_NO_ERROR(R.readStreamRef(SR, 0U));
   ArrayRef<uint8_t> Buffer;
   EXPECT_ERROR(SR.readBytes(0U, 1U, Buffer));
@@ -94,7 +94,7 @@
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
 
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str = "ZYXWVUTSRQPONMLKJIHGFEDCBA";
   EXPECT_NO_ERROR(R.readFixedString(Str, 1));
   EXPECT_EQ(Str, StringRef("A"));
@@ -108,7 +108,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str;
   EXPECT_NO_ERROR(R.readFixedString(Str, 2));
   EXPECT_EQ(Str, StringRef("AB"));
@@ -127,7 +127,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str;
   EXPECT_NO_ERROR(R.readFixedString(Str, 10));
   EXPECT_EQ(Str, StringRef("ABCDEFGHIJ"));
@@ -140,7 +140,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str;
 
   R.setOffset(10);
@@ -154,7 +154,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str;
 
   R.setOffset(6);
@@ -168,7 +168,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str;
 
   EXPECT_ERROR(R.readFixedString(Str, 11));
@@ -181,7 +181,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str;
   EXPECT_NO_ERROR(R.readFixedString(Str, 1));
   EXPECT_EQ(Str, StringRef("A"));
@@ -195,7 +195,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str1;
   StringRef Str2;
   EXPECT_NO_ERROR(R.readFixedString(Str1, 7));
@@ -216,7 +216,7 @@
   DiscontiguousStream F(BlocksAry, DataAry);
   auto S = MappedBlockStream::createStream(F.block_size(), F.block_count(),
                                            F.layout(), F);
-  StreamReader R(*S);
+  BinaryStreamReader R(*S, llvm::support::little);
   StringRef Str1;
   StringRef Str2;
   EXPECT_NO_ERROR(R.readFixedString(Str1, 6));
@@ -323,10 +323,10 @@
   uint32_t intArr1[] = {890723408, 29082234};
   ArrayRef<uint32_t> intArray[] = {intArr0, intArr1};
 
-  StreamReader Reader(*S);
-  StreamWriter Writer(*S);
-  EXPECT_NO_ERROR(Writer.writeInteger(u16[0], llvm::support::little));
-  EXPECT_NO_ERROR(Reader.readInteger(u16[1], llvm::support::little));
+  BinaryStreamReader Reader(*S, llvm::support::little);
+  BinaryStreamWriter Writer(*S, llvm::support::little);
+  EXPECT_NO_ERROR(Writer.writeInteger(u16[0]));
+  EXPECT_NO_ERROR(Reader.readInteger(u16[1]));
   EXPECT_EQ(u16[0], u16[1]);
   EXPECT_EQ(std::vector<uint8_t>({0, 0x7A, 0xEC, 0, 0, 0, 0, 0, 0, 0}),
             DataBytes);
@@ -334,8 +334,8 @@
   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
-  EXPECT_NO_ERROR(Writer.writeInteger(u32[0], llvm::support::little));
-  EXPECT_NO_ERROR(Reader.readInteger(u32[1], llvm::support::little));
+  EXPECT_NO_ERROR(Writer.writeInteger(u32[0]));
+  EXPECT_NO_ERROR(Reader.readInteger(u32[1]));
   EXPECT_EQ(u32[0], u32[1]);
   EXPECT_EQ(std::vector<uint8_t>({0x17, 0x5C, 0x50, 0, 0, 0, 0x35, 0, 0, 0}),
             DataBytes);
@@ -343,8 +343,8 @@
   Reader.setOffset(0);
   Writer.setOffset(0);
   ::memset(DataBytes.data(), 0, 10);
-  EXPECT_NO_ERROR(Writer.writeEnum(Enum[0], llvm::support::little));
-  EXPECT_NO_ERROR(Reader.readEnum(Enum[1], llvm::support::little));
+  EXPECT_NO_ERROR(Writer.writeEnum(Enum[0]));
+  EXPECT_NO_ERROR(Reader.readEnum(Enum[1]));
   EXPECT_EQ(Enum[0], Enum[1]);
   EXPECT_EQ(std::vector<uint8_t>({0x2C, 0x60, 0x4A, 0, 0, 0, 0, 0, 0, 0}),
             DataBytes);
@@ -399,21 +399,21 @@
       F.block_size(), F.block_count(), F.layout(), F);
 
   // First write "Test Str" into the source stream.
-  MutableByteStream SourceStream(SrcData);
-  StreamWriter SourceWriter(SourceStream);
+  MutableBinaryByteStream SourceStream(SrcData);
+  BinaryStreamWriter SourceWriter(SourceStream, llvm::support::little);
   EXPECT_NO_ERROR(SourceWriter.writeZeroString("Test Str"));
   EXPECT_EQ(SrcDataBytes, std::vector<uint8_t>(
                               {'T', 'e', 's', 't', ' ', 'S', 't', 'r', 0, 0}));
 
   // Then write the source stream into the dest stream.
-  StreamWriter DestWriter(*DestStream);
+  BinaryStreamWriter DestWriter(*DestStream, llvm::support::little);
   EXPECT_NO_ERROR(DestWriter.writeStreamRef(SourceStream));
   EXPECT_EQ(DestDataBytes, std::vector<uint8_t>(
                                {'s', 'e', 'T', ' ', 'S', 't', 't', 'r', 0, 0}));
 
   // Then read the string back out of the dest stream.
   StringRef Result;
-  StreamReader DestReader(*DestStream);
+  BinaryStreamReader DestReader(*DestStream, llvm::support::little);
   EXPECT_NO_ERROR(DestReader.readZeroString(Result));
   EXPECT_EQ(Result, "Test Str");
 }
@@ -436,20 +436,20 @@
       SrcF.block_size(), SrcF.block_count(), SrcF.layout(), SrcF);
 
   // First write "Test Str" into the source stream.
-  StreamWriter SourceWriter(*Src);
+  BinaryStreamWriter SourceWriter(*Src, llvm::support::little);
   EXPECT_NO_ERROR(SourceWriter.writeZeroString("Test Str"));
   EXPECT_EQ(SrcDataBytes, std::vector<uint8_t>(
                               {'e', 'T', 't', 't', ' ', 'S', 's', 'r', 0, 0}));
 
   // Then write the source stream into the dest stream.
-  StreamWriter DestWriter(*Dest);
+  BinaryStreamWriter DestWriter(*Dest, llvm::support::little);
   EXPECT_NO_ERROR(DestWriter.writeStreamRef(*Src));
   EXPECT_EQ(DestDataBytes, std::vector<uint8_t>(
                                {'s', 'e', 'T', ' ', 'S', 't', 't', 'r', 0, 0}));
 
   // Then read the string back out of the dest stream.
   StringRef Result;
-  StreamReader DestReader(*Dest);
+  BinaryStreamReader DestReader(*Dest, llvm::support::little);
   EXPECT_NO_ERROR(DestReader.readZeroString(Result));
   EXPECT_EQ(Result, "Test Str");
 }
Index: llvm/unittests/DebugInfo/PDB/StringTableBuilderTest.cpp
===================================================================
--- llvm/unittests/DebugInfo/PDB/StringTableBuilderTest.cpp
+++ llvm/unittests/DebugInfo/PDB/StringTableBuilderTest.cpp
@@ -9,11 +9,11 @@
 
 #include "ErrorChecking.h"
 
-#include "llvm/DebugInfo/MSF/ByteStream.h"
-#include "llvm/DebugInfo/MSF/StreamReader.h"
-#include "llvm/DebugInfo/MSF/StreamWriter.h"
 #include "llvm/DebugInfo/PDB/Native/StringTable.h"
 #include "llvm/DebugInfo/PDB/Native/StringTableBuilder.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
 
 #include "gtest/gtest.h"
 
@@ -33,13 +33,13 @@
   EXPECT_EQ(9U, Builder.insert("baz"));
 
   std::vector<uint8_t> Buffer(Builder.finalize());
-  msf::MutableByteStream OutStream(Buffer);
-  msf::StreamWriter Writer(OutStream);
+  MutableBinaryByteStream OutStream(Buffer);
+  BinaryStreamWriter Writer(OutStream, llvm::support::little);
   EXPECT_NO_ERROR(Builder.commit(Writer));
 
   // Reads the contents back.
-  msf::ByteStream InStream(Buffer);
-  msf::StreamReader Reader(InStream);
+  BinaryByteStream InStream(Buffer);
+  BinaryStreamReader Reader(InStream, llvm::support::little);
   StringTable Table;
   EXPECT_NO_ERROR(Table.load(Reader));
 
Index: llvm/unittests/Support/BinaryStreamTest.cpp
===================================================================
--- /dev/null
+++ llvm/unittests/Support/BinaryStreamTest.cpp
@@ -0,0 +1,698 @@
+//===- llvm/unittest/Support/BinaryStreamTest.cpp -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryItemStream.h"
+#include "llvm/Support/BinaryStreamArray.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+#include "gtest/gtest.h"
+
+#include <unordered_map>
+
+using namespace llvm;
+using namespace llvm::support;
+
+#define EXPECT_NO_ERROR(Err)                                                   \
+  {                                                                            \
+    auto E = Err;                                                              \
+    EXPECT_FALSE(static_cast<bool>(E));                                        \
+    if (E)                                                                     \
+      consumeError(std::move(E));                                              \
+  }
+
+#define ASSERT_NO_ERROR(Err)                                                   \
+  {                                                                            \
+    auto E = Err;                                                              \
+    ASSERT_FALSE(static_cast<bool>(E));                                        \
+    if (E)                                                                     \
+      consumeError(std::move(E));                                              \
+  }
+
+#define EXPECT_ERROR(Err)                                                      \
+  {                                                                            \
+    auto E = Err;                                                              \
+    EXPECT_TRUE(static_cast<bool>(E));                                         \
+    if (E)                                                                     \
+      consumeError(std::move(E));                                              \
+  }
+
+namespace {
+
+class DiscontiguousStream : public WritableBinaryStream {
+public:
+  explicit DiscontiguousStream(uint32_t Size = 0) : PartitionIndex(Size / 2) {
+    Data.resize(Size);
+  }
+
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) override {
+    if (Offset + Size > Data.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    uint32_t S = startIndex(Offset);
+    auto Ref = makeArrayRef(Data).drop_front(S);
+    if (Ref.size() >= Size) {
+      Buffer = Ref.take_front(Size);
+      return Error::success();
+    }
+
+    uint32_t BytesLeft = Size - Ref.size();
+    uint8_t *Ptr = Allocator.Allocate<uint8_t>(Size);
+    ::memcpy(Ptr, Ref.data(), Ref.size());
+    ::memcpy(Ptr + Ref.size(), Data.data(), BytesLeft);
+    Buffer = makeArrayRef<uint8_t>(Ptr, Size);
+    return Error::success();
+  }
+
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) override {
+    if (Offset >= Data.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    uint32_t S = startIndex(Offset);
+    Buffer = makeArrayRef(Data).drop_front(S);
+    return Error::success();
+  }
+
+  uint32_t getLength() override { return Data.size(); }
+
+  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> SrcData) override {
+    if (Offset + SrcData.size() > Data.size())
+      return errorCodeToError(make_error_code(std::errc::no_buffer_space));
+    if (SrcData.empty())
+      return Error::success();
+
+    uint32_t S = startIndex(Offset);
+    MutableArrayRef<uint8_t> Ref(Data);
+    Ref = Ref.drop_front(S);
+    if (Ref.size() >= SrcData.size()) {
+      ::memcpy(Ref.data(), SrcData.data(), SrcData.size());
+      return Error::success();
+    }
+
+    uint32_t BytesLeft = SrcData.size() - Ref.size();
+    ::memcpy(Ref.data(), SrcData.data(), Ref.size());
+    ::memcpy(&Data[0], SrcData.data() + Ref.size(), BytesLeft);
+    return Error::success();
+  }
+  Error commit() override { return Error::success(); }
+
+private:
+  uint32_t startIndex(uint32_t Offset) const {
+    return (Offset + PartitionIndex) % Data.size();
+  }
+
+  uint32_t endIndex(uint32_t Offset, uint32_t Size) const {
+    return (startIndex(Offset) + Size - 1) % Data.size();
+  }
+
+  uint32_t PartitionIndex = 0;
+  // Buffer is organized like this:
+  // -------------------------------------------------
+  // | N/2 | N/2+1 | ... | N-1 | 0 | 1 | ... | N-2-1 |
+  // -------------------------------------------------
+  // So reads from the beginning actually come from the middle.
+  mutable std::vector<uint8_t> Data;
+  mutable BumpPtrAllocator Allocator;
+};
+
+class BinaryStreamTest : public testing::Test {
+public:
+  BinaryStreamTest() {}
+
+  void SetUp() override {
+    InputData.clear();
+    OutputData.clear();
+    InputByteStream = BinaryByteStream();
+    InputBrokenStream = DiscontiguousStream();
+    OutputByteStream = MutableBinaryByteStream();
+    OutputBrokenStream = DiscontiguousStream();
+  }
+
+protected:
+  void initialize(ArrayRef<uint8_t> Input, uint32_t OutputSize) {
+    InputData = Input;
+
+    InputByteStream = BinaryByteStream(InputData);
+    InputBrokenStream = DiscontiguousStream(InputData.size());
+    consumeError(InputBrokenStream.writeBytes(0, Input));
+
+    OutputData.resize(OutputSize);
+    OutputByteStream = MutableBinaryByteStream(OutputData);
+    OutputBrokenStream = DiscontiguousStream(OutputSize);
+
+    InputStreams.push_back(&InputByteStream);
+    InputStreams.push_back(&InputBrokenStream);
+    OutputStreams.push_back(&OutputByteStream);
+    OutputStreams.push_back(&OutputBrokenStream);
+  }
+
+  void initialize(uint32_t OutputSize) {
+    initialize(std::vector<uint8_t>(), OutputSize);
+  }
+
+  std::vector<uint8_t> InputData;
+  std::vector<uint8_t> OutputData;
+
+  BinaryByteStream InputByteStream;
+  DiscontiguousStream InputBrokenStream;
+
+  MutableBinaryByteStream OutputByteStream;
+  DiscontiguousStream OutputBrokenStream;
+
+  std::vector<BinaryStream *> InputStreams;
+  std::vector<WritableBinaryStream *> OutputStreams;
+};
+
+// Tests that a we can read from a BinaryByteStream without a StreamReader.
+TEST_F(BinaryStreamTest, BinaryByteStreamProperties) {
+  std::vector<uint8_t> InputData = {1, 2, 3, 4, 5};
+  initialize(InputData, InputData.size());
+
+  for (auto Stream : InputStreams) {
+    ArrayRef<uint8_t> Buffer;
+
+    // 1. If the read fits it should work.
+    ASSERT_EQ(InputData.size(), Stream->getLength());
+    ASSERT_NO_ERROR(Stream->readBytes(2, 1, Buffer));
+    EXPECT_EQ(makeArrayRef(InputData).slice(2, 1), Buffer);
+    ASSERT_NO_ERROR(Stream->readBytes(0, 4, Buffer));
+    EXPECT_EQ(makeArrayRef(InputData).slice(0, 4), Buffer);
+
+    // 2. Reading past the bounds of the input should fail.
+    EXPECT_ERROR(Stream->readBytes(4, 2, Buffer));
+  }
+}
+
+// Test that we can write to a BinaryStream without a StreamWriter.
+TEST_F(BinaryStreamTest, MutableBinaryByteStreamProperties) {
+  std::vector<uint8_t> InputData = {'T', 'e', 's', 't', '\0'};
+  initialize(InputData, InputData.size());
+  ASSERT_EQ(2, InputStreams.size());
+  ASSERT_EQ(2, OutputStreams.size());
+
+  // For every combination of input stream and output stream.
+  for (auto IS : InputStreams) {
+    MutableArrayRef<uint8_t> Buffer;
+    ASSERT_EQ(InputData.size(), IS->getLength());
+
+    for (auto OS : OutputStreams) {
+
+      // 1. Try two reads that are supposed to work.  One from offset 0, and one
+      // from the middle.
+      uint32_t Offsets[] = {0, 3};
+      for (auto Offset : Offsets) {
+        uint32_t ExpectedSize = IS->getLength() - Offset;
+
+        // Read everything from Offset until the end of the input data.
+        ArrayRef<uint8_t> Data;
+        ASSERT_NO_ERROR(IS->readBytes(Offset, ExpectedSize, Data));
+        ASSERT_EQ(ExpectedSize, Data.size());
+
+        // Then write it to the destination.
+        ASSERT_NO_ERROR(OS->writeBytes(0, Data));
+
+        // Then we read back what we wrote, it should match the corresponding
+        // slice
+        // of the original input data.
+        ArrayRef<uint8_t> Data2;
+        ASSERT_NO_ERROR(OS->readBytes(Offset, ExpectedSize, Data2));
+        EXPECT_EQ(makeArrayRef(InputData).drop_front(Offset), Data2);
+      }
+
+      std::vector<uint8_t> BigData = {0, 1, 2, 3, 4};
+      // 2. If the write is too big, it should fail.
+      EXPECT_ERROR(OS->writeBytes(3, BigData));
+    }
+  }
+}
+
+// Test that FixedStreamArray works correctly.
+TEST_F(BinaryStreamTest, FixedStreamArray) {
+  std::vector<uint32_t> Ints = {90823, 12908, 109823, 209823};
+  ArrayRef<uint8_t> IntBytes(reinterpret_cast<uint8_t *>(Ints.data()),
+                             Ints.size() * sizeof(uint32_t));
+
+  initialize(IntBytes, 0);
+  ASSERT_EQ(2, InputStreams.size());
+
+  for (auto IS : InputStreams) {
+    MutableArrayRef<uint8_t> Buffer;
+    ASSERT_EQ(InputData.size(), IS->getLength());
+
+    FixedStreamArray<uint32_t> Array(*IS);
+    auto Iter = Array.begin();
+    ASSERT_EQ(Ints[0], *Iter++);
+    ASSERT_EQ(Ints[1], *Iter++);
+    ASSERT_EQ(Ints[2], *Iter++);
+    ASSERT_EQ(Ints[3], *Iter++);
+    ASSERT_EQ(Array.end(), Iter);
+  }
+}
+
+// Test that VarStreamArray works correctly.
+TEST_F(BinaryStreamTest, VarStreamArray) {
+  StringLiteral Strings("1. Test2. Longer Test3. Really Long Test4. Super "
+                        "Extra Longest Test Of All");
+  ArrayRef<uint8_t> StringBytes(
+      reinterpret_cast<const uint8_t *>(Strings.data()), Strings.size());
+  initialize(StringBytes, 0);
+
+  struct StringExtractor {
+  public:
+    Error operator()(BinaryStreamRef Stream, uint32_t &Len, StringRef &Item) {
+      if (Index == 0)
+        Len = strlen("1. Test");
+      else if (Index == 1)
+        Len = strlen("2. Longer Test");
+      else if (Index == 2)
+        Len = strlen("3. Really Long Test");
+      else
+        Len = strlen("4. Super Extra Longest Test Of All");
+      ArrayRef<uint8_t> Bytes;
+      if (auto EC = Stream.readBytes(0, Len, Bytes))
+        return EC;
+      Item =
+          StringRef(reinterpret_cast<const char *>(Bytes.data()), Bytes.size());
+      ++Index;
+      return Error::success();
+    }
+
+  private:
+    uint32_t Index = 0;
+  };
+
+  for (auto IS : InputStreams) {
+    VarStreamArray<StringRef, StringExtractor> Array(*IS);
+    auto Iter = Array.begin();
+    ASSERT_EQ("1. Test", *Iter++);
+    ASSERT_EQ("2. Longer Test", *Iter++);
+    ASSERT_EQ("3. Really Long Test", *Iter++);
+    ASSERT_EQ("4. Super Extra Longest Test Of All", *Iter++);
+    ASSERT_EQ(Array.end(), Iter);
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamReaderBounds) {
+  std::vector<uint8_t> Bytes;
+
+  initialize(Bytes, 0);
+  for (auto IS : InputStreams) {
+    StringRef S;
+    BinaryStreamReader Reader(*IS, little);
+    EXPECT_EQ(0, Reader.bytesRemaining());
+    EXPECT_ERROR(Reader.readFixedString(S, 1));
+  }
+
+  Bytes.resize(5);
+  initialize(Bytes, 0);
+  for (auto IS : InputStreams) {
+    StringRef S;
+    BinaryStreamReader Reader(*IS, little);
+    EXPECT_EQ(Bytes.size(), Reader.bytesRemaining());
+    EXPECT_NO_ERROR(Reader.readFixedString(S, 5));
+    EXPECT_ERROR(Reader.readFixedString(S, 6));
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamReaderIntegers) {
+  support::ulittle64_t Little{908234};
+  support::ubig32_t Big{28907823};
+  short NS = 2897;
+  int NI = -89723;
+  unsigned long NUL = 902309023UL;
+  constexpr uint32_t Size =
+      sizeof(Little) + sizeof(Big) + sizeof(NS) + sizeof(NI) + sizeof(NUL);
+  std::vector<uint8_t> Bytes(Size);
+  uint8_t *Ptr = &Bytes[0];
+  memcpy(Ptr, &Little, sizeof(Little));
+  Ptr += sizeof(Little);
+  memcpy(Ptr, &Big, sizeof(Big));
+  Ptr += sizeof(Big);
+  memcpy(Ptr, &NS, sizeof(NS));
+  Ptr += sizeof(NS);
+  memcpy(Ptr, &NI, sizeof(NI));
+  Ptr += sizeof(NI);
+  memcpy(Ptr, &NUL, sizeof(NUL));
+  Ptr += sizeof(NUL);
+
+  initialize(Bytes, 0);
+  for (auto IS : InputStreams) {
+    const support::ulittle64_t *Little2;
+    const support::ubig32_t *Big2;
+    short NS2;
+    int NI2;
+    unsigned long NUL2;
+
+    // 1. Reading fields individually.
+    BinaryStreamReader Reader(*IS, little);
+    ASSERT_NO_ERROR(Reader.readObject(Little2));
+    ASSERT_NO_ERROR(Reader.readObject(Big2));
+    ASSERT_NO_ERROR(Reader.readInteger(NS2));
+    ASSERT_NO_ERROR(Reader.readInteger(NI2));
+    ASSERT_NO_ERROR(Reader.readInteger(NUL2));
+    ASSERT_EQ(0, Reader.bytesRemaining());
+
+    EXPECT_EQ(Little, *Little2);
+    EXPECT_EQ(Big, *Big2);
+    EXPECT_EQ(NS, NS2);
+    EXPECT_EQ(NI, NI2);
+    EXPECT_EQ(NUL, NUL2);
+
+    // 2. Reading with explicit endianness.
+    Reader.setOffset(0);
+    const ulittle64_t *Little3;
+    const ubig32_t *Big3;
+    ASSERT_NO_ERROR(Reader.readObject(Little3));
+    ASSERT_NO_ERROR(Reader.readObject(Big3));
+    EXPECT_EQ(Little, *Little3);
+    EXPECT_EQ(Big, *Big3);
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamReaderIntegerArray) {
+  // 1. Arrays of integers
+  std::vector<int> Ints = {1, 2, 3, 4, 5};
+  ArrayRef<uint8_t> IntBytes(reinterpret_cast<uint8_t *>(&Ints[0]),
+                             Ints.size() * sizeof(int));
+  initialize(IntBytes, 0);
+  for (auto IS : InputStreams) {
+    BinaryStreamReader Reader(*IS, little);
+    ArrayRef<int> IntsRef;
+    ASSERT_NO_ERROR(Reader.readArray(IntsRef, Ints.size()));
+    ASSERT_EQ(0, Reader.bytesRemaining());
+    EXPECT_EQ(makeArrayRef(Ints), IntsRef);
+
+    Reader.setOffset(0);
+    FixedStreamArray<int> FixedIntsRef;
+    ASSERT_NO_ERROR(Reader.readArray(FixedIntsRef, Ints.size()));
+    ASSERT_EQ(0, Reader.bytesRemaining());
+    ASSERT_EQ(Ints, std::vector<int>(FixedIntsRef.begin(), FixedIntsRef.end()));
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamReaderEnum) {
+  enum class MyEnum : int64_t { Foo = -10, Bar = 0, Baz = 10 };
+
+  std::vector<MyEnum> Enums = {MyEnum::Bar, MyEnum::Baz, MyEnum::Foo};
+
+  ArrayRef<uint8_t> Bytes(reinterpret_cast<const uint8_t *>(&Enums[0]),
+                          sizeof(MyEnum) * Enums.size());
+
+  initialize(Bytes, 0);
+  for (auto IS : InputStreams) {
+    BinaryStreamReader Reader(*IS, little);
+
+    MyEnum V1;
+    MyEnum V2;
+    MyEnum V3;
+    ArrayRef<MyEnum> Array;
+    FixedStreamArray<MyEnum> FSA;
+
+    ASSERT_NO_ERROR(Reader.readEnum(V1));
+    ASSERT_NO_ERROR(Reader.readEnum(V2));
+    ASSERT_NO_ERROR(Reader.readEnum(V3));
+    ASSERT_EQ(0, Reader.bytesRemaining());
+
+    EXPECT_EQ(MyEnum::Bar, V1);
+    EXPECT_EQ(MyEnum::Baz, V2);
+    EXPECT_EQ(MyEnum::Foo, V3);
+
+    Reader.setOffset(0);
+    ASSERT_NO_ERROR(Reader.readArray(Array, 3));
+    EXPECT_EQ(makeArrayRef(Enums), Array);
+
+    Reader.setOffset(0);
+    ASSERT_NO_ERROR(Reader.readArray(FSA, 3));
+    EXPECT_EQ(Enums, std::vector<MyEnum>(FSA.begin(), FSA.end()));
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamReaderObject) {
+  struct Foo {
+    int X;
+    double Y;
+    char Z;
+  };
+
+  std::vector<Foo> Foos;
+  Foos.push_back({-42, 42.42, 42});
+  Foos.push_back({100, 3.1415, -89});
+
+  std::vector<uint8_t> Bytes;
+  Bytes.resize(2 * sizeof(Foo));
+  Foo *FPtr = reinterpret_cast<Foo *>(&Bytes[0]);
+  Foo *GPtr = FPtr + 1;
+
+  ::memcpy(FPtr, &Foos[0], sizeof(Foo));
+  ::memcpy(GPtr + sizeof(Foo), &Foos[1], sizeof(Foo));
+
+  initialize(Bytes, 0);
+
+  for (auto IS : InputStreams) {
+    // 1. Reading object pointers.
+    BinaryStreamReader Reader(*IS, little);
+    const Foo *FPtrOut = nullptr;
+    const Foo *GPtrOut = nullptr;
+    ASSERT_NO_ERROR(Reader.readObject(FPtrOut));
+    ASSERT_NO_ERROR(Reader.readObject(GPtrOut));
+    EXPECT_EQ(0, Reader.bytesRemaining());
+    EXPECT_EQ(0, ::memcmp(FPtr, FPtrOut, sizeof(Foo)));
+    EXPECT_EQ(0, ::memcmp(GPtr, GPtrOut, sizeof(Foo)));
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamReaderStrings) {
+  StringLiteral Strings("One\0"
+                        "Two\0"
+                        "Three\0"
+                        "Four\0");
+  ArrayRef<uint8_t> Bytes(Strings.bytes_begin(), Strings.bytes_end());
+  initialize(Bytes, 0);
+
+  for (auto IS : InputStreams) {
+    BinaryStreamReader Reader(*IS, little);
+
+    StringRef S1;
+    StringRef S2;
+    StringRef S3;
+    StringRef S4;
+    ASSERT_NO_ERROR(Reader.readZeroString(S1));
+    ASSERT_NO_ERROR(Reader.readZeroString(S2));
+    ASSERT_NO_ERROR(Reader.readZeroString(S3));
+    ASSERT_NO_ERROR(Reader.readZeroString(S4));
+    ASSERT_EQ(0, Reader.bytesRemaining());
+
+    EXPECT_EQ("One", S1);
+    EXPECT_EQ("Two", S2);
+    EXPECT_EQ("Three", S3);
+    EXPECT_EQ("Four", S4);
+
+    S1 = S2 = S3 = S4 = "";
+    Reader.setOffset(0);
+    ASSERT_NO_ERROR(Reader.readFixedString(S1, 3));
+    ASSERT_NO_ERROR(Reader.skip(1));
+    ASSERT_NO_ERROR(Reader.readFixedString(S2, 3));
+    ASSERT_NO_ERROR(Reader.skip(1));
+    ASSERT_NO_ERROR(Reader.readFixedString(S3, 5));
+    ASSERT_NO_ERROR(Reader.skip(1));
+    ASSERT_NO_ERROR(Reader.readFixedString(S4, 4));
+    ASSERT_NO_ERROR(Reader.skip(1));
+    ASSERT_EQ(0, Reader.bytesRemaining());
+
+    EXPECT_EQ("One", S1);
+    EXPECT_EQ("Two", S2);
+    EXPECT_EQ("Three", S3);
+    EXPECT_EQ("Four", S4);
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamWriterBounds) {
+  initialize(5);
+
+  for (auto OS : OutputStreams) {
+    BinaryStreamWriter Writer(*OS, little);
+
+    // 1. Can write a string that exactly fills the buffer.
+    EXPECT_EQ(5, Writer.bytesRemaining());
+    EXPECT_NO_ERROR(Writer.writeFixedString("abcde"));
+    EXPECT_EQ(0, Writer.bytesRemaining());
+
+    // 2. Can write an empty string even when you're full
+    EXPECT_NO_ERROR(Writer.writeFixedString(""));
+    EXPECT_ERROR(Writer.writeFixedString("a"));
+
+    // 3. Can't write a string that is one character too long.
+    Writer.setOffset(0);
+    EXPECT_ERROR(Writer.writeFixedString("abcdef"));
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamWriterIntegers) {
+  support::ulittle64_t Little{908234};
+  support::ubig32_t Big{28907823};
+  short NS = 2897;
+  int NI = -89723;
+  unsigned long NUL = 902309023UL;
+  constexpr uint32_t Size =
+      sizeof(Little) + sizeof(Big) + sizeof(NS) + sizeof(NI) + sizeof(NUL);
+
+  initialize(Size);
+
+  for (auto OS : OutputStreams) {
+    BinaryStreamWriter Writer(*OS, little);
+
+    // 1. Writing fields individually.
+    ASSERT_NO_ERROR(Writer.writeObject(Little));
+    ASSERT_NO_ERROR(Writer.writeObject(Big));
+    ASSERT_NO_ERROR(Writer.writeInteger(NS));
+    ASSERT_NO_ERROR(Writer.writeInteger(NI));
+    ASSERT_NO_ERROR(Writer.writeInteger(NUL));
+    ASSERT_EQ(0, Writer.bytesRemaining());
+
+    // Read them back in and confirm they're correct.
+    const ulittle64_t *Little2;
+    const ubig32_t *Big2;
+    short NS2;
+    int NI2;
+    unsigned long NUL2;
+    BinaryStreamReader Reader(*OS, little);
+    ASSERT_NO_ERROR(Reader.readObject(Little2));
+    ASSERT_NO_ERROR(Reader.readObject(Big2));
+    ASSERT_NO_ERROR(Reader.readInteger(NS2));
+    ASSERT_NO_ERROR(Reader.readInteger(NI2));
+    ASSERT_NO_ERROR(Reader.readInteger(NUL2));
+    EXPECT_EQ(Little, *Little2);
+    EXPECT_EQ(Big, *Big2);
+    EXPECT_EQ(NS, NS2);
+    EXPECT_EQ(NI, NI2);
+    EXPECT_EQ(NUL, NUL2);
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamWriterIntegerArrays) {
+  // 3. Arrays of integers
+  std::vector<int> SourceInts = {1, 2, 3, 4, 5};
+  ArrayRef<uint8_t> SourceBytes(reinterpret_cast<uint8_t *>(&SourceInts[0]),
+                                SourceInts.size() * sizeof(int));
+
+  initialize(SourceBytes, SourceBytes.size());
+
+  for (auto IS : InputStreams) {
+    for (auto OS : OutputStreams) {
+      BinaryStreamReader Reader(*IS, little);
+      BinaryStreamWriter Writer(*OS, little);
+      ArrayRef<int> Ints;
+      ArrayRef<int> Ints2;
+      // First read them, then write them, then read them back.
+      ASSERT_NO_ERROR(Reader.readArray(Ints, SourceInts.size()));
+      ASSERT_NO_ERROR(Writer.writeArray(Ints));
+
+      BinaryStreamReader ReaderBacker(*OS, little);
+      ASSERT_NO_ERROR(ReaderBacker.readArray(Ints2, SourceInts.size()));
+
+      EXPECT_EQ(makeArrayRef(SourceInts), Ints2);
+    }
+  }
+}
+
+TEST_F(BinaryStreamTest, StreamWriterEnum) {
+  enum class MyEnum : int64_t { Foo = -10, Bar = 0, Baz = 10 };
+
+  std::vector<MyEnum> Expected = {MyEnum::Bar, MyEnum::Foo, MyEnum::Baz};
+
+  initialize(Expected.size() * sizeof(MyEnum));
+
+  for (auto OS : OutputStreams) {
+    BinaryStreamWriter Writer(*OS, little);
+    ArrayRef<MyEnum> Enums;
+    ArrayRef<MyEnum> Enums2;
+
+    // First read them, then write them, then read them back.
+    for (auto ME : Expected)
+      ASSERT_NO_ERROR(Writer.writeEnum(ME));
+
+    ArrayRef<MyEnum> Array;
+    BinaryStreamReader Reader(*OS, little);
+    ASSERT_NO_ERROR(Reader.readArray(Array, Expected.size()));
+
+    EXPECT_EQ(makeArrayRef(Expected), Array);
+  }
+}
+}
+
+namespace {
+struct BinaryItemStreamObject {
+  BinaryItemStreamObject(int X, StringRef Y, float Z) : X(X), Y(Y), Z(Z) {}
+
+  // Note the use of std::string here, so this class cannot just be memcpy'ed.
+  int X;
+  std::string Y;
+  float Z;
+};
+}
+
+namespace llvm {
+template <> struct BinaryItemTraits<std::unique_ptr<BinaryItemStreamObject>> {
+  size_t length(const std::unique_ptr<BinaryItemStreamObject> &Item) {
+    size_t S = sizeof(Item->X); // X
+    S += Item->Y.size() + 1;    // Y + null terminator
+    S += sizeof(Item->Z);       // Z
+    return S;
+  }
+
+  ArrayRef<uint8_t> bytes(const std::unique_ptr<BinaryItemStreamObject> &Item) {
+    // In practice we probably would use a more cheaply serializable type,
+    // or at the very least not allocate every single time.  This is just
+    // for illustration and testing though.
+    size_t Size = length(Item);
+    uint8_t *Buffer = Alloc.Allocate<uint8_t>(Size);
+    MutableBinaryByteStream Stream(MutableArrayRef<uint8_t>(Buffer, Size));
+    BinaryStreamWriter Writer(Stream, llvm::support::little);
+    consumeError(Writer.writeInteger(Item->X));
+    consumeError(Writer.writeZeroString(Item->Y));
+    consumeError(Writer.writeObject(Item->Z));
+    return makeArrayRef(Buffer, Size);
+  }
+
+private:
+  BumpPtrAllocator Alloc;
+};
+}
+
+namespace {
+
+TEST_F(BinaryStreamTest, BinaryItemStream) {
+  // Note that this is a vector of pointers, so individual records do not live
+  // contiguously in memory.
+  std::vector<std::unique_ptr<BinaryItemStreamObject>> Objects;
+  Objects.push_back(llvm::make_unique<BinaryItemStreamObject>(1, "First", 1.0));
+  Objects.push_back(
+      llvm::make_unique<BinaryItemStreamObject>(2, "Second", 2.0));
+  Objects.push_back(llvm::make_unique<BinaryItemStreamObject>(3, "Third", 3.0));
+
+  BinaryItemStream<std::unique_ptr<BinaryItemStreamObject>> ItemStream;
+  ItemStream.setItems(Objects);
+  BinaryStreamReader Reader(ItemStream, llvm::support::little);
+
+  for (int I = 0; I < 3; ++I) {
+    int X;
+    StringRef Y;
+    const float *Z;
+    ASSERT_NO_ERROR(Reader.readInteger(X));
+    ASSERT_NO_ERROR(Reader.readZeroString(Y));
+    ASSERT_NO_ERROR(Reader.readObject(Z));
+
+    EXPECT_EQ(Objects[I]->X, X);
+    EXPECT_EQ(Objects[I]->Y, Y);
+    EXPECT_DOUBLE_EQ(Objects[I]->Z, *Z);
+  }
+}
+
+} // end anonymous namespace
Index: llvm/unittests/Support/CMakeLists.txt
===================================================================
--- llvm/unittests/Support/CMakeLists.txt
+++ llvm/unittests/Support/CMakeLists.txt
@@ -7,6 +7,7 @@
   AllocatorTest.cpp
   ARMAttributeParser.cpp
   ArrayRecyclerTest.cpp
+  BinaryStreamTest.cpp
   BlockFrequencyTest.cpp
   BranchProbabilityTest.cpp
   Casting.cpp