Index: lld/COFF/PDB.cpp
===================================================================
--- lld/COFF/PDB.cpp
+++ lld/COFF/PDB.cpp
@@ -18,6 +18,7 @@
 #include "llvm/DebugInfo/CodeView/CVDebugRecord.h"
 #include "llvm/DebugInfo/CodeView/DebugSubsectionRecord.h"
 #include "llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h"
+#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/RecordName.h"
 #include "llvm/DebugInfo/CodeView/SymbolDeserializer.h"
 #include "llvm/DebugInfo/CodeView/SymbolSerializer.h"
@@ -25,7 +26,6 @@
 #include "llvm/DebugInfo/CodeView/TypeDumpVisitor.h"
 #include "llvm/DebugInfo/CodeView/TypeIndexDiscovery.h"
 #include "llvm/DebugInfo/CodeView/TypeStreamMerger.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
 #include "llvm/DebugInfo/MSF/MSFCommon.h"
 #include "llvm/DebugInfo/PDB/GenericError.h"
@@ -118,10 +118,10 @@
   pdb::PDBFileBuilder Builder;
 
   /// Type records that will go into the PDB TPI stream.
-  TypeTableBuilder TypeTable;
+  MergingTypeTableBuilder TypeTable;
 
   /// Item records that will go into the PDB IPI stream.
-  TypeTableBuilder IDTable;
+  MergingTypeTableBuilder IDTable;
 
   /// PDBs use a single global string table for filenames in the file checksum
   /// table.
Index: llvm/include/llvm/DebugInfo/CodeView/AppendingTypeTableBuilder.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/DebugInfo/CodeView/AppendingTypeTableBuilder.h
@@ -0,0 +1,70 @@
+//===- AppendingTypeTableBuilder.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_CODEVIEW_APPENDINGTYPETABLEBUILDER_H
+#define LLVM_DEBUGINFO_CODEVIEW_APPENDINGTYPETABLEBUILDER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/DebugInfo/CodeView/CodeView.h"
+#include "llvm/DebugInfo/CodeView/SimpleTypeSerializer.h"
+#include "llvm/DebugInfo/CodeView/TypeCollection.h"
+#include "llvm/DebugInfo/CodeView/TypeIndex.h"
+#include "llvm/Support/Allocator.h"
+#include <cassert>
+#include <cstdint>
+#include <memory>
+#include <vector>
+
+namespace llvm {
+namespace codeview {
+
+class ContinuationRecordBuilder;
+
+class AppendingTypeTableBuilder : public TypeCollection {
+
+  BumpPtrAllocator &RecordStorage;
+  SimpleTypeSerializer SimpleSerializer;
+
+  /// Contains a list of all records indexed by TypeIndex.toArrayIndex().
+  SmallVector<ArrayRef<uint8_t>, 2> SeenRecords;
+
+public:
+  explicit AppendingTypeTableBuilder(BumpPtrAllocator &Storage);
+  ~AppendingTypeTableBuilder();
+
+  // TypeTableCollection overrides
+  Optional<TypeIndex> getFirst() override;
+  Optional<TypeIndex> getNext(TypeIndex Prev) override;
+  CVType getType(TypeIndex Index) override;
+  StringRef getTypeName(TypeIndex Index) override;
+  bool contains(TypeIndex Index) override;
+  uint32_t size() override;
+  uint32_t capacity() override;
+
+  // public interface
+  void reset();
+  TypeIndex nextTypeIndex() const;
+
+  BumpPtrAllocator &getAllocator() { return RecordStorage; }
+
+  ArrayRef<ArrayRef<uint8_t>> records() const;
+  TypeIndex insertRecordBytes(ArrayRef<uint8_t> &Record);
+  TypeIndex insertRecord(ContinuationRecordBuilder &Builder);
+
+  template <typename T> TypeIndex writeLeafType(T &Record) {
+    ArrayRef<uint8_t> Data = SimpleSerializer.serialize(Record);
+    return insertRecordBytes(Data);
+  }
+};
+
+} // end namespace codeview
+} // end namespace llvm
+
+#endif // LLVM_DEBUGINFO_CODEVIEW_TYPETABLEBUILDER_H
Index: llvm/include/llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h
+++ llvm/include/llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h
@@ -1,4 +1,4 @@
-//===- TypeTableBuilder.h ----------------------------------------*- C++-*-===//
+//===- MergingTypeTableBuilder.h ---------------------------------*- C++-*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_DEBUGINFO_CODEVIEW_TYPETABLEBUILDER_H
-#define LLVM_DEBUGINFO_CODEVIEW_TYPETABLEBUILDER_H
+#ifndef LLVM_DEBUGINFO_CODEVIEW_MERGINGTYPETABLEBUILDER_H
+#define LLVM_DEBUGINFO_CODEVIEW_MERGINGTYPETABLEBUILDER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
@@ -31,7 +31,7 @@
 class ContinuationRecordBuilder;
 class TypeHasher;
 
-class TypeTableBuilder : public TypeCollection {
+class MergingTypeTableBuilder : public TypeCollection {
 
   BumpPtrAllocator &RecordStorage;
   SimpleTypeSerializer SimpleSerializer;
@@ -43,8 +43,8 @@
   SmallVector<ArrayRef<uint8_t>, 2> SeenRecords;
 
 public:
-  explicit TypeTableBuilder(BumpPtrAllocator &Storage, bool Hash = true);
-  ~TypeTableBuilder();
+  explicit MergingTypeTableBuilder(BumpPtrAllocator &Storage);
+  ~MergingTypeTableBuilder();
 
   // TypeTableCollection overrides
   Optional<TypeIndex> getFirst() override;
@@ -74,4 +74,4 @@
 } // end namespace codeview
 } // end namespace llvm
 
-#endif // LLVM_DEBUGINFO_CODEVIEW_TYPETABLEBUILDER_H
+#endif // LLVM_DEBUGINFO_CODEVIEW_MERGINGTYPETABLEBUILDER_H
Index: llvm/include/llvm/DebugInfo/CodeView/TypeStreamMerger.h
===================================================================
--- llvm/include/llvm/DebugInfo/CodeView/TypeStreamMerger.h
+++ llvm/include/llvm/DebugInfo/CodeView/TypeStreamMerger.h
@@ -19,7 +19,7 @@
 namespace codeview {
 
 class TypeIndex;
-class TypeTableBuilder;
+class MergingTypeTableBuilder;
 
 /// \brief Merge one set of type records into another.  This method assumes
 /// that all records are type records, and there are no Id records present.
@@ -34,7 +34,7 @@
 ///
 /// \returns Error::success() if the operation succeeded, otherwise an
 /// appropriate error code.
-Error mergeTypeRecords(TypeTableBuilder &Dest,
+Error mergeTypeRecords(MergingTypeTableBuilder &Dest,
                        SmallVectorImpl<TypeIndex> &SourceToDest,
                        const CVTypeArray &Types);
 
@@ -59,7 +59,7 @@
 ///
 /// \returns Error::success() if the operation succeeded, otherwise an
 /// appropriate error code.
-Error mergeIdRecords(TypeTableBuilder &Dest, ArrayRef<TypeIndex> Types,
+Error mergeIdRecords(MergingTypeTableBuilder &Dest, ArrayRef<TypeIndex> Types,
                      SmallVectorImpl<TypeIndex> &SourceToDest,
                      const CVTypeArray &Ids);
 
@@ -78,8 +78,8 @@
 ///
 /// \returns Error::success() if the operation succeeded, otherwise an
 /// appropriate error code.
-Error mergeTypeAndIdRecords(TypeTableBuilder &DestIds,
-                            TypeTableBuilder &DestTypes,
+Error mergeTypeAndIdRecords(MergingTypeTableBuilder &DestIds,
+                            MergingTypeTableBuilder &DestTypes,
                             SmallVectorImpl<TypeIndex> &SourceToDest,
                             const CVTypeArray &IdsAndTypes);
 
Index: llvm/include/llvm/ObjectYAML/CodeViewYAMLTypes.h
===================================================================
--- llvm/include/llvm/ObjectYAML/CodeViewYAMLTypes.h
+++ llvm/include/llvm/ObjectYAML/CodeViewYAMLTypes.h
@@ -27,7 +27,7 @@
 namespace llvm {
 
 namespace codeview {
-class TypeTableBuilder;
+class AppendingTypeTableBuilder;
 }
 
 namespace CodeViewYAML {
@@ -47,7 +47,7 @@
   std::shared_ptr<detail::LeafRecordBase> Leaf;
 
   codeview::CVType
-  toCodeViewRecord(codeview::TypeTableBuilder &Serializer) const;
+  toCodeViewRecord(codeview::AppendingTypeTableBuilder &Serializer) const;
   static Expected<LeafRecord> fromCodeViewRecord(codeview::CVType Type);
 };
 
Index: llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -23,8 +23,8 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/DebugInfo/CodeView/CodeView.h"
+#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/IR/DebugLoc.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Compiler.h"
@@ -52,7 +52,7 @@
 class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
   MCStreamer &OS;
   BumpPtrAllocator Allocator;
-  codeview::TypeTableBuilder TypeTable;
+  codeview::MergingTypeTableBuilder TypeTable;
 
   /// Represents the most general definition range.
   struct LocalVarDefRange {
Index: llvm/lib/DebugInfo/CodeView/AppendingTypeTableBuilder.cpp
===================================================================
--- /dev/null
+++ llvm/lib/DebugInfo/CodeView/AppendingTypeTableBuilder.cpp
@@ -0,0 +1,101 @@
+//===- AppendingTypeTableBuilder.cpp --------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/CodeView/AppendingTypeTableBuilder.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/DebugInfo/CodeView/CodeView.h"
+#include "llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h"
+#include "llvm/DebugInfo/CodeView/RecordSerialization.h"
+#include "llvm/DebugInfo/CodeView/TypeIndex.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Error.h"
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+
+using namespace llvm;
+using namespace llvm::codeview;
+
+TypeIndex AppendingTypeTableBuilder::nextTypeIndex() const {
+  return TypeIndex::fromArrayIndex(SeenRecords.size());
+}
+
+AppendingTypeTableBuilder::AppendingTypeTableBuilder(BumpPtrAllocator &Storage)
+    : RecordStorage(Storage) {}
+
+AppendingTypeTableBuilder::~AppendingTypeTableBuilder() = default;
+
+Optional<TypeIndex> AppendingTypeTableBuilder::getFirst() {
+  if (empty())
+    return None;
+
+  return TypeIndex(TypeIndex::FirstNonSimpleIndex);
+}
+
+Optional<TypeIndex> AppendingTypeTableBuilder::getNext(TypeIndex Prev) {
+  if (++Prev == nextTypeIndex())
+    return None;
+  return Prev;
+}
+
+CVType AppendingTypeTableBuilder::getType(TypeIndex Index) {
+  CVType Type;
+  Type.RecordData = SeenRecords[Index.toArrayIndex()];
+  const RecordPrefix *P =
+      reinterpret_cast<const RecordPrefix *>(Type.RecordData.data());
+  Type.Type = static_cast<TypeLeafKind>(uint16_t(P->RecordKind));
+  return Type;
+}
+
+StringRef AppendingTypeTableBuilder::getTypeName(TypeIndex Index) {
+  llvm_unreachable("Method not implemented");
+}
+
+bool AppendingTypeTableBuilder::contains(TypeIndex Index) {
+  if (Index.isSimple() || Index.isNoneType())
+    return false;
+
+  return Index.toArrayIndex() < SeenRecords.size();
+}
+
+uint32_t AppendingTypeTableBuilder::size() { return SeenRecords.size(); }
+
+uint32_t AppendingTypeTableBuilder::capacity() { return SeenRecords.size(); }
+
+ArrayRef<ArrayRef<uint8_t>> AppendingTypeTableBuilder::records() const {
+  return SeenRecords;
+}
+
+void AppendingTypeTableBuilder::reset() { SeenRecords.clear(); }
+
+TypeIndex
+AppendingTypeTableBuilder::insertRecordBytes(ArrayRef<uint8_t> &Record) {
+  TypeIndex NewTI = nextTypeIndex();
+  uint8_t *Stable = RecordStorage.Allocate<uint8_t>(Record.size());
+  memcpy(Stable, Record.data(), Record.size());
+  Record = ArrayRef<uint8_t>(Stable, Record.size());
+  SeenRecords.push_back(Record);
+  return NewTI;
+}
+
+TypeIndex
+AppendingTypeTableBuilder::insertRecord(ContinuationRecordBuilder &Builder) {
+  TypeIndex TI;
+  auto Fragments = Builder.end(nextTypeIndex());
+  assert(!Fragments.empty());
+  for (auto C : Fragments)
+    TI = insertRecordBytes(C.RecordData);
+  return TI;
+}
Index: llvm/lib/DebugInfo/CodeView/CMakeLists.txt
===================================================================
--- llvm/lib/DebugInfo/CodeView/CMakeLists.txt
+++ llvm/lib/DebugInfo/CodeView/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_llvm_library(LLVMDebugInfoCodeView
+  AppendingTypeTableBuilder.cpp
   CodeViewError.cpp
   CodeViewRecordIO.cpp
   ContinuationRecordBuilder.cpp
@@ -20,6 +21,7 @@
   Formatters.cpp
   LazyRandomTypeCollection.cpp
   Line.cpp
+  MergingTypeTableBuilder.cpp
   RecordName.cpp
   RecordSerialization.cpp
   SimpleTypeSerializer.cpp
@@ -31,7 +33,6 @@
   TypeIndex.cpp
   TypeIndexDiscovery.cpp
   TypeRecordMapping.cpp
-  TypeTableBuilder.cpp
   TypeStreamMerger.cpp
   TypeTableCollection.cpp
 
Index: llvm/lib/DebugInfo/CodeView/MergingTypeTableBuilder.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/MergingTypeTableBuilder.cpp
+++ llvm/lib/DebugInfo/CodeView/MergingTypeTableBuilder.cpp
@@ -1,4 +1,4 @@
-//===- TypeSerialzier.cpp -------------------------------------------------===//
+//===- MergingTypeTableBuilder.cpp ----------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
+#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
@@ -130,32 +130,31 @@
   return Hashed->Index;
 }
 
-TypeIndex TypeTableBuilder::nextTypeIndex() const {
+TypeIndex MergingTypeTableBuilder::nextTypeIndex() const {
   return TypeIndex::fromArrayIndex(SeenRecords.size());
 }
 
-TypeTableBuilder::TypeTableBuilder(BumpPtrAllocator &Storage, bool Hash)
+MergingTypeTableBuilder::MergingTypeTableBuilder(BumpPtrAllocator &Storage)
     : RecordStorage(Storage) {
-  if (Hash)
-    Hasher = llvm::make_unique<TypeHasher>(Storage);
+  Hasher = llvm::make_unique<TypeHasher>(Storage);
 }
 
-TypeTableBuilder::~TypeTableBuilder() = default;
+MergingTypeTableBuilder::~MergingTypeTableBuilder() = default;
 
-Optional<TypeIndex> TypeTableBuilder::getFirst() {
+Optional<TypeIndex> MergingTypeTableBuilder::getFirst() {
   if (empty())
     return None;
 
   return TypeIndex(TypeIndex::FirstNonSimpleIndex);
 }
 
-Optional<TypeIndex> TypeTableBuilder::getNext(TypeIndex Prev) {
+Optional<TypeIndex> MergingTypeTableBuilder::getNext(TypeIndex Prev) {
   if (++Prev == nextTypeIndex())
     return None;
   return Prev;
 }
 
-CVType TypeTableBuilder::getType(TypeIndex Index) {
+CVType MergingTypeTableBuilder::getType(TypeIndex Index) {
   CVType Type;
   Type.RecordData = SeenRecords[Index.toArrayIndex()];
   const RecordPrefix *P =
@@ -164,48 +163,40 @@
   return Type;
 }
 
-StringRef TypeTableBuilder::getTypeName(TypeIndex Index) {
+StringRef MergingTypeTableBuilder::getTypeName(TypeIndex Index) {
   llvm_unreachable("Method not implemented");
 }
 
-bool TypeTableBuilder::contains(TypeIndex Index) {
+bool MergingTypeTableBuilder::contains(TypeIndex Index) {
   if (Index.isSimple() || Index.isNoneType())
     return false;
 
   return Index.toArrayIndex() < SeenRecords.size();
 }
 
-uint32_t TypeTableBuilder::size() { return SeenRecords.size(); }
+uint32_t MergingTypeTableBuilder::size() { return SeenRecords.size(); }
 
-uint32_t TypeTableBuilder::capacity() { return SeenRecords.size(); }
+uint32_t MergingTypeTableBuilder::capacity() { return SeenRecords.size(); }
 
-ArrayRef<ArrayRef<uint8_t>> TypeTableBuilder::records() const {
+ArrayRef<ArrayRef<uint8_t>> MergingTypeTableBuilder::records() const {
   return SeenRecords;
 }
 
-void TypeTableBuilder::reset() {
-  if (Hasher)
-    Hasher->reset();
+void MergingTypeTableBuilder::reset() {
+  Hasher->reset();
   SeenRecords.clear();
 }
 
-TypeIndex TypeTableBuilder::insertRecordBytes(ArrayRef<uint8_t> &Record) {
-  if (Hasher) {
-    TypeIndex ActualTI = Hasher->getOrCreateRecord(Record, nextTypeIndex());
-    if (nextTypeIndex() == ActualTI)
-      SeenRecords.push_back(Record);
-    return ActualTI;
-  }
-
-  TypeIndex NewTI = nextTypeIndex();
-  uint8_t *Stable = RecordStorage.Allocate<uint8_t>(Record.size());
-  memcpy(Stable, Record.data(), Record.size());
-  Record = ArrayRef<uint8_t>(Stable, Record.size());
-  SeenRecords.push_back(Record);
-  return NewTI;
+TypeIndex
+MergingTypeTableBuilder::insertRecordBytes(ArrayRef<uint8_t> &Record) {
+  TypeIndex ActualTI = Hasher->getOrCreateRecord(Record, nextTypeIndex());
+  if (nextTypeIndex() == ActualTI)
+    SeenRecords.push_back(Record);
+  return ActualTI;
 }
 
-TypeIndex TypeTableBuilder::insertRecord(ContinuationRecordBuilder &Builder) {
+TypeIndex
+MergingTypeTableBuilder::insertRecord(ContinuationRecordBuilder &Builder) {
   TypeIndex TI;
   auto Fragments = Builder.end(nextTypeIndex());
   assert(!Fragments.empty());
Index: llvm/lib/DebugInfo/CodeView/TypeStreamMerger.cpp
===================================================================
--- llvm/lib/DebugInfo/CodeView/TypeStreamMerger.cpp
+++ llvm/lib/DebugInfo/CodeView/TypeStreamMerger.cpp
@@ -10,11 +10,11 @@
 #include "llvm/DebugInfo/CodeView/TypeStreamMerger.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/TypeDeserializer.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeIndexDiscovery.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ScopedPrinter.h"
 
@@ -64,12 +64,14 @@
 
   static const TypeIndex Untranslated;
 
-  Error mergeTypesAndIds(TypeTableBuilder &DestIds, TypeTableBuilder &DestTypes,
+  Error mergeTypesAndIds(MergingTypeTableBuilder &DestIds,
+                         MergingTypeTableBuilder &DestTypes,
                          const CVTypeArray &IdsAndTypes);
-  Error mergeIdRecords(TypeTableBuilder &Dest,
+  Error mergeIdRecords(MergingTypeTableBuilder &Dest,
                        ArrayRef<TypeIndex> TypeSourceToDest,
                        const CVTypeArray &Ids);
-  Error mergeTypeRecords(TypeTableBuilder &Dest, const CVTypeArray &Types);
+  Error mergeTypeRecords(MergingTypeTableBuilder &Dest,
+                         const CVTypeArray &Types);
 
 private:
   Error doit(const CVTypeArray &Types);
@@ -106,8 +108,8 @@
 
   TypeIndex CurIndex{TypeIndex::FirstNonSimpleIndex};
 
-  TypeTableBuilder *DestIdStream = nullptr;
-  TypeTableBuilder *DestTypeStream = nullptr;
+  MergingTypeTableBuilder *DestIdStream = nullptr;
+  MergingTypeTableBuilder *DestTypeStream = nullptr;
 
   // If we're only mapping id records, this array contains the mapping for
   // type records.
@@ -221,14 +223,14 @@
   return remapIndex(Idx, IndexMap);
 }
 
-Error TypeStreamMerger::mergeTypeRecords(TypeTableBuilder &Dest,
+Error TypeStreamMerger::mergeTypeRecords(MergingTypeTableBuilder &Dest,
                                          const CVTypeArray &Types) {
   DestTypeStream = &Dest;
 
   return doit(Types);
 }
 
-Error TypeStreamMerger::mergeIdRecords(TypeTableBuilder &Dest,
+Error TypeStreamMerger::mergeIdRecords(MergingTypeTableBuilder &Dest,
                                        ArrayRef<TypeIndex> TypeSourceToDest,
                                        const CVTypeArray &Ids) {
   DestIdStream = &Dest;
@@ -237,8 +239,8 @@
   return doit(Ids);
 }
 
-Error TypeStreamMerger::mergeTypesAndIds(TypeTableBuilder &DestIds,
-                                         TypeTableBuilder &DestTypes,
+Error TypeStreamMerger::mergeTypesAndIds(MergingTypeTableBuilder &DestIds,
+                                         MergingTypeTableBuilder &DestTypes,
                                          const CVTypeArray &IdsAndTypes) {
   DestIdStream = &DestIds;
   DestTypeStream = &DestTypes;
@@ -286,7 +288,7 @@
 }
 
 Error TypeStreamMerger::remapType(const CVType &Type) {
-  TypeTableBuilder &Dest =
+  MergingTypeTableBuilder &Dest =
       isIdRecord(Type.kind()) ? *DestIdStream : *DestTypeStream;
 
   RemappedType R(Type);
@@ -329,14 +331,14 @@
   return Success;
 }
 
-Error llvm::codeview::mergeTypeRecords(TypeTableBuilder &Dest,
+Error llvm::codeview::mergeTypeRecords(MergingTypeTableBuilder &Dest,
                                        SmallVectorImpl<TypeIndex> &SourceToDest,
                                        const CVTypeArray &Types) {
   TypeStreamMerger M(SourceToDest);
   return M.mergeTypeRecords(Dest, Types);
 }
 
-Error llvm::codeview::mergeIdRecords(TypeTableBuilder &Dest,
+Error llvm::codeview::mergeIdRecords(MergingTypeTableBuilder &Dest,
                                      ArrayRef<TypeIndex> TypeSourceToDest,
                                      SmallVectorImpl<TypeIndex> &SourceToDest,
                                      const CVTypeArray &Ids) {
@@ -345,7 +347,7 @@
 }
 
 Error llvm::codeview::mergeTypeAndIdRecords(
-    TypeTableBuilder &DestIds, TypeTableBuilder &DestTypes,
+    MergingTypeTableBuilder &DestIds, MergingTypeTableBuilder &DestTypes,
     SmallVectorImpl<TypeIndex> &SourceToDest, const CVTypeArray &IdsAndTypes) {
   TypeStreamMerger M(SourceToDest);
   return M.mergeTypesAndIds(DestIds, DestTypes, IdsAndTypes);
Index: llvm/lib/ObjectYAML/CodeViewYAMLTypes.cpp
===================================================================
--- llvm/lib/ObjectYAML/CodeViewYAMLTypes.cpp
+++ llvm/lib/ObjectYAML/CodeViewYAMLTypes.cpp
@@ -17,13 +17,13 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/BinaryFormat/COFF.h"
+#include "llvm/DebugInfo/CodeView/AppendingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/CVTypeVisitor.h"
 #include "llvm/DebugInfo/CodeView/CodeView.h"
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
 #include "llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h"
 #include "llvm/DebugInfo/CodeView/TypeDeserializer.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/BinaryStreamReader.h"
@@ -83,7 +83,7 @@
   virtual ~LeafRecordBase() = default;
 
   virtual void map(yaml::IO &io) = 0;
-  virtual CVType toCodeViewRecord(TypeTableBuilder &TS) const = 0;
+  virtual CVType toCodeViewRecord(AppendingTypeTableBuilder &TS) const = 0;
   virtual Error fromCodeViewRecord(CVType Type) = 0;
 };
 
@@ -97,7 +97,7 @@
     return TypeDeserializer::deserializeAs<T>(Type, Record);
   }
 
-  CVType toCodeViewRecord(TypeTableBuilder &TS) const override {
+  CVType toCodeViewRecord(AppendingTypeTableBuilder &TS) const override {
     TS.writeLeafType(Record);
     return CVType(Kind, TS.records().back());
   }
@@ -109,7 +109,7 @@
   explicit LeafRecordImpl(TypeLeafKind K) : LeafRecordBase(K) {}
 
   void map(yaml::IO &io) override;
-  CVType toCodeViewRecord(TypeTableBuilder &TS) const override;
+  CVType toCodeViewRecord(AppendingTypeTableBuilder &TS) const override;
   Error fromCodeViewRecord(CVType Type) override;
 
   std::vector<MemberRecord> Members;
@@ -489,8 +489,8 @@
   return visitMemberRecordStream(Type.content(), V);
 }
 
-CVType
-LeafRecordImpl<FieldListRecord>::toCodeViewRecord(TypeTableBuilder &TS) const {
+CVType LeafRecordImpl<FieldListRecord>::toCodeViewRecord(
+    AppendingTypeTableBuilder &TS) const {
   ContinuationRecordBuilder CRB;
   CRB.begin(ContinuationRecordKind::FieldList);
   for (const auto &Member : Members) {
@@ -682,7 +682,8 @@
   return make_error<CodeViewError>(cv_error_code::corrupt_record);
 }
 
-CVType LeafRecord::toCodeViewRecord(TypeTableBuilder &Serializer) const {
+CVType
+LeafRecord::toCodeViewRecord(AppendingTypeTableBuilder &Serializer) const {
   return Leaf->toCodeViewRecord(Serializer);
 }
 
@@ -782,7 +783,7 @@
 
 ArrayRef<uint8_t> llvm::CodeViewYAML::toDebugT(ArrayRef<LeafRecord> Leafs,
                                                BumpPtrAllocator &Alloc) {
-  TypeTableBuilder TS(Alloc, false);
+  AppendingTypeTableBuilder TS(Alloc);
   uint32_t Size = sizeof(uint32_t);
   for (const auto &Leaf : Leafs) {
     CVType T = Leaf.Leaf->toCodeViewRecord(TS);
Index: llvm/tools/llvm-pdbutil/llvm-pdbutil.cpp
===================================================================
--- llvm/tools/llvm-pdbutil/llvm-pdbutil.cpp
+++ llvm/tools/llvm-pdbutil/llvm-pdbutil.cpp
@@ -35,13 +35,14 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/BinaryFormat/Magic.h"
 #include "llvm/Config/config.h"
+#include "llvm/DebugInfo/CodeView/AppendingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/DebugChecksumsSubsection.h"
 #include "llvm/DebugInfo/CodeView/DebugInlineeLinesSubsection.h"
 #include "llvm/DebugInfo/CodeView/DebugLinesSubsection.h"
 #include "llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h"
+#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/StringsAndChecksums.h"
 #include "llvm/DebugInfo/CodeView/TypeStreamMerger.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
 #include "llvm/DebugInfo/PDB/GenericError.h"
 #include "llvm/DebugInfo/PDB/IPDBEnumChildren.h"
@@ -727,7 +728,7 @@
   auto &TpiBuilder = Builder.getTpiBuilder();
   const auto &Tpi = YamlObj.TpiStream.getValueOr(DefaultTpiStream);
   TpiBuilder.setVersionHeader(Tpi.Version);
-  TypeTableBuilder TS(Allocator);
+  AppendingTypeTableBuilder TS(Allocator);
   for (const auto &R : Tpi.Records) {
     CVType Type = R.toCodeViewRecord(TS);
     TpiBuilder.addTypeRecord(Type.RecordData, None);
@@ -989,8 +990,8 @@
 
 static void mergePdbs() {
   BumpPtrAllocator Allocator;
-  TypeTableBuilder MergedTpi(Allocator);
-  TypeTableBuilder MergedIpi(Allocator);
+  MergingTypeTableBuilder MergedTpi(Allocator);
+  MergingTypeTableBuilder MergedIpi(Allocator);
 
   // Create a Tpi and Ipi type table with all types from all input files.
   for (const auto &Path : opts::merge::InputFilenames) {
Index: llvm/tools/llvm-readobj/COFFDumper.cpp
===================================================================
--- llvm/tools/llvm-readobj/COFFDumper.cpp
+++ llvm/tools/llvm-readobj/COFFDumper.cpp
@@ -31,6 +31,7 @@
 #include "llvm/DebugInfo/CodeView/DebugStringTableSubsection.h"
 #include "llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h"
 #include "llvm/DebugInfo/CodeView/Line.h"
+#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/RecordSerialization.h"
 #include "llvm/DebugInfo/CodeView/SymbolDeserializer.h"
 #include "llvm/DebugInfo/CodeView/SymbolDumpDelegate.h"
@@ -40,7 +41,6 @@
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeStreamMerger.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/TypeTableCollection.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Object/ObjectFile.h"
@@ -96,8 +96,9 @@
   void printCOFFResources() override;
   void printCOFFLoadConfig() override;
   void printCodeViewDebugInfo() override;
-  void mergeCodeViewTypes(llvm::codeview::TypeTableBuilder &CVIDs,
-                          llvm::codeview::TypeTableBuilder &CVTypes) override;
+  void
+  mergeCodeViewTypes(llvm::codeview::MergingTypeTableBuilder &CVIDs,
+                     llvm::codeview::MergingTypeTableBuilder &CVTypes) override;
   void printStackMap() const override;
 private:
   void printSymbol(const SymbolRef &Sym);
@@ -1194,8 +1195,8 @@
   W.printHex(Label, getFileNameForFileOffset(FileOffset), FileOffset);
 }
 
-void COFFDumper::mergeCodeViewTypes(TypeTableBuilder &CVIDs,
-                                    TypeTableBuilder &CVTypes) {
+void COFFDumper::mergeCodeViewTypes(MergingTypeTableBuilder &CVIDs,
+                                    MergingTypeTableBuilder &CVTypes) {
   for (const SectionRef &S : Obj->sections()) {
     StringRef SectionName;
     error(S.getName(SectionName));
@@ -1803,9 +1804,9 @@
                         StackMapV2Parser<support::big>(StackMapContentsArray));
 }
 
-void llvm::dumpCodeViewMergedTypes(ScopedPrinter &Writer,
-                                   llvm::codeview::TypeTableBuilder &IDTable,
-                                   llvm::codeview::TypeTableBuilder &CVTypes) {
+void llvm::dumpCodeViewMergedTypes(
+    ScopedPrinter &Writer, llvm::codeview::MergingTypeTableBuilder &IDTable,
+    llvm::codeview::MergingTypeTableBuilder &CVTypes) {
   // Flatten it first, then run our dumper on it.
   SmallString<0> TypeBuf;
   CVTypes.ForEachRecord([&](TypeIndex TI, const CVType &Record) {
Index: llvm/tools/llvm-readobj/ObjDumper.h
===================================================================
--- llvm/tools/llvm-readobj/ObjDumper.h
+++ llvm/tools/llvm-readobj/ObjDumper.h
@@ -19,7 +19,7 @@
 class ObjectFile;
 }
 namespace codeview {
-class TypeTableBuilder;
+class MergingTypeTableBuilder;
 }
 
 class ScopedPrinter;
@@ -67,8 +67,9 @@
   virtual void printCOFFResources() {}
   virtual void printCOFFLoadConfig() { }
   virtual void printCodeViewDebugInfo() { }
-  virtual void mergeCodeViewTypes(llvm::codeview::TypeTableBuilder &CVIDs,
-                                  llvm::codeview::TypeTableBuilder &CVTypes) {}
+  virtual void
+  mergeCodeViewTypes(llvm::codeview::MergingTypeTableBuilder &CVIDs,
+                     llvm::codeview::MergingTypeTableBuilder &CVTypes) {}
 
   // Only implemented for MachO.
   virtual void printMachODataInCode() { }
@@ -102,9 +103,9 @@
 
 void dumpCOFFImportFile(const object::COFFImportFile *File);
 
-void dumpCodeViewMergedTypes(ScopedPrinter &Writer,
-                             llvm::codeview::TypeTableBuilder &IDTable,
-                             llvm::codeview::TypeTableBuilder &TypeTable);
+void dumpCodeViewMergedTypes(
+    ScopedPrinter &Writer, llvm::codeview::MergingTypeTableBuilder &IDTable,
+    llvm::codeview::MergingTypeTableBuilder &TypeTable);
 
 } // namespace llvm
 
Index: llvm/tools/llvm-readobj/llvm-readobj.cpp
===================================================================
--- llvm/tools/llvm-readobj/llvm-readobj.cpp
+++ llvm/tools/llvm-readobj/llvm-readobj.cpp
@@ -23,7 +23,7 @@
 #include "Error.h"
 #include "ObjDumper.h"
 #include "WindowsResourceDumper.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
+#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/ELFObjectFile.h"
@@ -353,8 +353,8 @@
       : Allocator(), IDTable(Allocator), TypeTable(Allocator) {}
 
   llvm::BumpPtrAllocator Allocator;
-  llvm::codeview::TypeTableBuilder IDTable;
-  llvm::codeview::TypeTableBuilder TypeTable;
+  llvm::codeview::MergingTypeTableBuilder IDTable;
+  llvm::codeview::MergingTypeTableBuilder TypeTable;
 };
 }
 static ReadObjTypeTableBuilder CVTypes;
@@ -566,13 +566,13 @@
   cl::ParseCommandLineOptions(argc, argv, "LLVM Object Reader\n");
 
   // Default to stdin if no filename is specified.
-  if (opts::InputFilenames.size() == 0)
-    opts::InputFilenames.push_back("-");
-
-  llvm::for_each(opts::InputFilenames, dumpInput);
-
-  if (opts::CodeViewMergedTypes) {
-    ScopedPrinter W(outs());
+  if (opts::InputFilenames.size() == 0)
+    opts::InputFilenames.push_back("-");
+
+  llvm::for_each(opts::InputFilenames, dumpInput);
+
+  if (opts::CodeViewMergedTypes) {
+    ScopedPrinter W(outs());
     dumpCodeViewMergedTypes(W, CVTypes.IDTable, CVTypes.TypeTable);
   }
 
Index: llvm/unittests/DebugInfo/CodeView/RandomAccessVisitorTest.cpp
===================================================================
--- llvm/unittests/DebugInfo/CodeView/RandomAccessVisitorTest.cpp
+++ llvm/unittests/DebugInfo/CodeView/RandomAccessVisitorTest.cpp
@@ -8,11 +8,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/SmallBitVector.h"
+#include "llvm/DebugInfo/CodeView/AppendingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/CVTypeVisitor.h"
 #include "llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeRecordMapping.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
 #include "llvm/Support/Allocator.h"
@@ -94,7 +94,7 @@
   static void SetUpTestCase() {
     GlobalState = llvm::make_unique<GlobalTestState>();
 
-    TypeTableBuilder Builder(GlobalState->Allocator);
+    AppendingTypeTableBuilder Builder(GlobalState->Allocator);
 
     uint32_t Offset = 0;
     for (int I = 0; I < 11; ++I) {
@@ -351,7 +351,7 @@
 }
 
 TEST_F(RandomAccessVisitorTest, CrossChunkName) {
-  TypeTableBuilder Builder(GlobalState->Allocator);
+  AppendingTypeTableBuilder Builder(GlobalState->Allocator);
 
   // TypeIndex 0
   ClassRecord Class(TypeRecordKind::Class);
Index: llvm/unittests/DebugInfo/CodeView/TypeIndexDiscoveryTest.cpp
===================================================================
--- llvm/unittests/DebugInfo/CodeView/TypeIndexDiscoveryTest.cpp
+++ llvm/unittests/DebugInfo/CodeView/TypeIndexDiscoveryTest.cpp
@@ -9,9 +9,9 @@
 
 #include "llvm/DebugInfo/CodeView/TypeIndexDiscovery.h"
 
+#include "llvm/DebugInfo/CodeView/AppendingTypeTableBuilder.h"
 #include "llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h"
 #include "llvm/DebugInfo/CodeView/SymbolSerializer.h"
-#include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
 #include "llvm/Support/Allocator.h"
 
 #include "gmock/gmock.h"
@@ -26,7 +26,7 @@
 
   void SetUp() override {
     Refs.clear();
-    TTB = make_unique<TypeTableBuilder>(Storage);
+    TTB = make_unique<AppendingTypeTableBuilder>(Storage);
     CRB = make_unique<ContinuationRecordBuilder>();
     Symbols.clear();
   }
@@ -76,8 +76,7 @@
     discoverTypeIndicesInSymbols();
   }
 
-
-  std::unique_ptr<TypeTableBuilder> TTB;
+  std::unique_ptr<AppendingTypeTableBuilder> TTB;
 
 private:
   uint32_t countRefs(uint32_t RecordIndex) const {