diff --git a/llvm/include/llvm/Bitcode/BitcodeAnalyzer.h b/llvm/include/llvm/Bitcode/BitcodeAnalyzer.h
--- a/llvm/include/llvm/Bitcode/BitcodeAnalyzer.h
+++ b/llvm/include/llvm/Bitcode/BitcodeAnalyzer.h
@@ -18,12 +18,13 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Bitstream/BitstreamReader.h"
 #include "llvm/Support/Error.h"
-#include "llvm/Support/raw_ostream.h"
 #include <map>
 #include <vector>
 
 namespace llvm {
 
+class raw_ostream;
+
 /// CurStreamTypeType - A type for CurStreamType
 enum CurStreamTypeType {
   UnknownBitstream,
diff --git a/llvm/include/llvm/Bitcode/BitcodeReader.h b/llvm/include/llvm/Bitcode/BitcodeReader.h
--- a/llvm/include/llvm/Bitcode/BitcodeReader.h
+++ b/llvm/include/llvm/Bitcode/BitcodeReader.h
@@ -16,11 +16,10 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Bitstream/BitCodes.h"
-#include "llvm/IR/ModuleSummaryIndex.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorOr.h"
-#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/MemoryBufferRef.h"
 #include <cstdint>
 #include <memory>
 #include <string>
@@ -30,6 +29,8 @@
 
 class LLVMContext;
 class Module;
+class MemoryBuffer;
+class ModuleSummaryIndex;
 
 typedef llvm::function_ref<Optional<std::string>(StringRef)>
     DataLayoutCallbackTy;
diff --git a/llvm/lib/Bitcode/Reader/BitReader.cpp b/llvm/lib/Bitcode/Reader/BitReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitReader.cpp
@@ -12,7 +12,6 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/raw_ostream.h"
 #include <cstring>
 #include <string>
 
diff --git a/llvm/lib/Bitcode/Reader/MetadataLoader.h b/llvm/lib/Bitcode/Reader/MetadataLoader.h
--- a/llvm/lib/Bitcode/Reader/MetadataLoader.h
+++ b/llvm/lib/Bitcode/Reader/MetadataLoader.h
@@ -13,7 +13,6 @@
 #ifndef LLVM_LIB_BITCODE_READER_METADATALOADER_H
 #define LLVM_LIB_BITCODE_READER_METADATALOADER_H
 
-#include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Error.h"
 
 #include <functional>
@@ -28,6 +27,7 @@
 class Metadata;
 class Module;
 class Type;
+template <typename T> class ArrayRef;
 
 /// Helper class that handles loading Metadatas and keeping them available.
 class MetadataLoader {
@@ -66,8 +66,8 @@
   DISubprogram *lookupSubprogramForFunction(Function *F);
 
   /// Parse a `METADATA_ATTACHMENT` block for a function.
-  Error parseMetadataAttachment(
-      Function &F, const SmallVectorImpl<Instruction *> &InstructionList);
+  Error parseMetadataAttachment(Function &F,
+                                ArrayRef<Instruction *> InstructionList);
 
   /// Parse a `METADATA_KIND` block for the current module.
   Error parseMetadataKinds();
diff --git a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
--- a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
+++ b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
@@ -9,75 +9,60 @@
 #include "MetadataLoader.h"
 #include "ValueList.h"
 
-#include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/BitmaskEnum.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/None.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/ADT/ilist_iterator.h"
+#include "llvm/ADT/iterator_range.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/Bitcode/LLVMBitCodes.h"
 #include "llvm/Bitstream/BitstreamReader.h"
-#include "llvm/IR/Argument.h"
-#include "llvm/IR/Attributes.h"
 #include "llvm/IR/AutoUpgrade.h"
 #include "llvm/IR/BasicBlock.h"
-#include "llvm/IR/CallingConv.h"
-#include "llvm/IR/Comdat.h"
-#include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
-#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DebugInfoMetadata.h"
-#include "llvm/IR/DebugLoc.h"
-#include "llvm/IR/DerivedTypes.h"
-#include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/GVMaterializer.h"
-#include "llvm/IR/GlobalAlias.h"
-#include "llvm/IR/GlobalIFunc.h"
 #include "llvm/IR/GlobalObject.h"
-#include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/GlobalVariable.h"
-#include "llvm/IR/InlineAsm.h"
-#include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
-#include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
-#include "llvm/IR/ModuleSummaryIndex.h"
-#include "llvm/IR/OperandTraits.h"
 #include "llvm/IR/TrackingMDRef.h"
 #include "llvm/IR/Type.h"
-#include "llvm/IR/ValueHandle.h"
-#include "llvm/Support/AtomicOrdering.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
-#include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/ManagedStatic.h"
-#include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/type_traits.h"
+
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <deque>
+#include <iterator>
 #include <limits>
-#include <map>
 #include <string>
-#include <system_error>
 #include <tuple>
+#include <type_traits>
 #include <utility>
 #include <vector>
+namespace llvm {
+class Argument;
+}
 
 using namespace llvm;
 
@@ -679,8 +664,8 @@
 
   bool hasSeenOldLoopTags() const { return HasSeenOldLoopTags; }
 
-  Error parseMetadataAttachment(
-      Function &F, const SmallVectorImpl<Instruction *> &InstructionList);
+  Error parseMetadataAttachment(Function &F,
+                                ArrayRef<Instruction *> InstructionList);
 
   Error parseMetadataKinds();
 
@@ -2182,7 +2167,7 @@
 
 /// Parse metadata attachments.
 Error MetadataLoader::MetadataLoaderImpl::parseMetadataAttachment(
-    Function &F, const SmallVectorImpl<Instruction *> &InstructionList) {
+    Function &F, ArrayRef<Instruction *> InstructionList) {
   if (Error Err = Stream.EnterSubBlock(bitc::METADATA_ATTACHMENT_ID))
     return Err;
 
@@ -2358,7 +2343,7 @@
 }
 
 Error MetadataLoader::parseMetadataAttachment(
-    Function &F, const SmallVectorImpl<Instruction *> &InstructionList) {
+    Function &F, ArrayRef<Instruction *> InstructionList) {
   return Pimpl->parseMetadataAttachment(F, InstructionList);
 }
 
diff --git a/llvm/lib/Bitcode/Reader/ValueList.cpp b/llvm/lib/Bitcode/Reader/ValueList.cpp
--- a/llvm/lib/Bitcode/Reader/ValueList.cpp
+++ b/llvm/lib/Bitcode/Reader/ValueList.cpp
@@ -18,9 +18,7 @@
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
-#include <algorithm>
 #include <cstddef>
-#include <limits>
 
 using namespace llvm;
 
diff --git a/llvm/tools/llvm-dis/llvm-dis.cpp b/llvm/tools/llvm-dis/llvm-dis.cpp
--- a/llvm/tools/llvm-dis/llvm-dis.cpp
+++ b/llvm/tools/llvm-dis/llvm-dis.cpp
@@ -23,6 +23,7 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/ModuleSummaryIndex.h"
 #include "llvm/IR/Type.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"