diff --git a/llvm/include/llvm/Analysis/SparsePropagation.h b/llvm/include/llvm/Analysis/SparsePropagation.h
index 6eb6d5518a41b2..428238c5fa0bcd 100644
--- a/llvm/include/llvm/Analysis/SparsePropagation.h
+++ b/llvm/include/llvm/Analysis/SparsePropagation.h
@@ -15,6 +15,7 @@
 #define LLVM_ANALYSIS_SPARSEPROPAGATION_H
 
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/Support/Debug.h"
 #include <set>
diff --git a/llvm/include/llvm/Analysis/TargetFolder.h b/llvm/include/llvm/Analysis/TargetFolder.h
index 1fd16add07d1b7..df4267f5fb6452 100644
--- a/llvm/include/llvm/Analysis/TargetFolder.h
+++ b/llvm/include/llvm/Analysis/TargetFolder.h
@@ -20,6 +20,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/IRBuilderFolder.h"
 
 namespace llvm {
diff --git a/llvm/include/llvm/Analysis/ValueLattice.h b/llvm/include/llvm/Analysis/ValueLattice.h
index 1b3b02c0844195..bc6b279e9ed52b 100644
--- a/llvm/include/llvm/Analysis/ValueLattice.h
+++ b/llvm/include/llvm/Analysis/ValueLattice.h
@@ -9,9 +9,10 @@
 #ifndef LLVM_ANALYSIS_VALUELATTICE_H
 #define LLVM_ANALYSIS_VALUELATTICE_H
 
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/Instructions.h"
-//
+
 //===----------------------------------------------------------------------===//
 //                               ValueLatticeElement
 //===----------------------------------------------------------------------===//
diff --git a/llvm/include/llvm/IR/AbstractCallSite.h b/llvm/include/llvm/IR/AbstractCallSite.h
index 69048554a05cbd..50afe016f0d633 100644
--- a/llvm/include/llvm/IR/AbstractCallSite.h
+++ b/llvm/include/llvm/IR/AbstractCallSite.h
@@ -14,17 +14,17 @@
 #ifndef LLVM_IR_ABSTRACTCALLSITE_H
 #define LLVM_IR_ABSTRACTCALLSITE_H
 
-#include "llvm/IR/Argument.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/InstrTypes.h"
-#include "llvm/IR/Use.h"
 #include "llvm/IR/Value.h"
-#include "llvm/Support/Casting.h"
 #include <cassert>
 
 namespace llvm {
 
+class Argument;
+class Use;
+
 /// AbstractCallSite
 ///
 /// An abstract call site is a wrapper that allows to treat direct,
diff --git a/llvm/include/llvm/IR/Argument.h b/llvm/include/llvm/IR/Argument.h
index 7cbfa2a7b6cec8..3b74853cdafa17 100644
--- a/llvm/include/llvm/IR/Argument.h
+++ b/llvm/include/llvm/IR/Argument.h
@@ -14,7 +14,6 @@
 #define LLVM_IR_ARGUMENT_H
 
 #include "llvm/ADT/Twine.h"
-#include "llvm/ADT/ilist_node.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Value.h"
 
diff --git a/llvm/include/llvm/IR/AutoUpgrade.h b/llvm/include/llvm/IR/AutoUpgrade.h
index b0db790da99d17..bcece46f89e02c 100644
--- a/llvm/include/llvm/IR/AutoUpgrade.h
+++ b/llvm/include/llvm/IR/AutoUpgrade.h
@@ -21,9 +21,10 @@ namespace llvm {
   class Constant;
   class Function;
   class Instruction;
+  class GlobalVariable;
   class MDNode;
   class Module;
-  class GlobalVariable;
+  class StringRef;
   class Type;
   class Value;
 
diff --git a/llvm/include/llvm/IR/BasicBlock.h b/llvm/include/llvm/IR/BasicBlock.h
index 184ddfc01c296e..3204ec76b340d5 100644
--- a/llvm/include/llvm/IR/BasicBlock.h
+++ b/llvm/include/llvm/IR/BasicBlock.h
@@ -22,9 +22,6 @@
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/SymbolTableListTraits.h"
 #include "llvm/IR/Value.h"
-#include "llvm/Support/CBindingWrapping.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Support/Compiler.h"
 #include <cassert>
 #include <cstddef>
 #include <iterator>
diff --git a/llvm/include/llvm/IR/CFG.h b/llvm/include/llvm/IR/CFG.h
index 0ee584f8af7ed1..28a8d31a4cc609 100644
--- a/llvm/include/llvm/IR/CFG.h
+++ b/llvm/include/llvm/IR/CFG.h
@@ -25,7 +25,6 @@
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Value.h"
-#include "llvm/Support/Casting.h"
 #include <cassert>
 #include <cstddef>
 #include <iterator>
diff --git a/llvm/include/llvm/IR/ConstantFolder.h b/llvm/include/llvm/IR/ConstantFolder.h
index 28dc63a5886e5f..6ec316ea61c4f9 100644
--- a/llvm/include/llvm/IR/ConstantFolder.h
+++ b/llvm/include/llvm/IR/ConstantFolder.h
@@ -20,7 +20,6 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/IRBuilderFolder.h"
-#include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
 
 namespace llvm {
diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index 1b9843e08b28a5..a0aeec5f1af9f7 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -32,8 +32,6 @@
 #include "llvm/IR/OperandTraits.h"
 #include "llvm/IR/SymbolTableListTraits.h"
 #include "llvm/IR/Value.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Support/Compiler.h"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
diff --git a/llvm/include/llvm/IR/InstVisitor.h b/llvm/include/llvm/IR/InstVisitor.h
index 585129904dd4d3..89bf234c9de7c8 100644
--- a/llvm/include/llvm/IR/InstVisitor.h
+++ b/llvm/include/llvm/IR/InstVisitor.h
@@ -15,7 +15,6 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/Module.h"
-#include "llvm/Support/ErrorHandling.h"
 
 namespace llvm {
 
diff --git a/llvm/include/llvm/IR/InstrTypes.h b/llvm/include/llvm/IR/InstrTypes.h
index b50a02c5dde52c..58f867cb11e187 100644
--- a/llvm/include/llvm/IR/InstrTypes.h
+++ b/llvm/include/llvm/IR/InstrTypes.h
@@ -21,22 +21,16 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Sequence.h"
 #include "llvm/ADT/StringMap.h"
-#include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/CallingConv.h"
-#include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/OperandTraits.h"
-#include "llvm/IR/Type.h"
 #include "llvm/IR/User.h"
-#include "llvm/IR/Value.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
@@ -47,6 +41,10 @@
 
 namespace llvm {
 
+class StringRef;
+class Type;
+class Value;
+
 namespace Intrinsic {
 typedef unsigned ID;
 }
diff --git a/llvm/include/llvm/IR/Instruction.h b/llvm/include/llvm/IR/Instruction.h
index 1937ffd36f7b12..8d0a8363cdfb48 100644
--- a/llvm/include/llvm/IR/Instruction.h
+++ b/llvm/include/llvm/IR/Instruction.h
@@ -24,7 +24,6 @@
 #include "llvm/IR/User.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/AtomicOrdering.h"
-#include "llvm/Support/Casting.h"
 #include <cstdint>
 #include <utility>
 
diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index 5929cff3b4fb31..e9ea6c6d86c34e 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -21,24 +21,18 @@
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.h"
-#include "llvm/IR/Attributes.h"
-#include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/OperandTraits.h"
-#include "llvm/IR/Type.h"
 #include "llvm/IR/Use.h"
 #include "llvm/IR/User.h"
-#include "llvm/IR/Value.h"
 #include "llvm/Support/AtomicOrdering.h"
-#include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
 #include <cstddef>
@@ -47,9 +41,14 @@
 
 namespace llvm {
 
+class APFloat;
 class APInt;
+class BasicBlock;
 class ConstantInt;
 class DataLayout;
+class StringRef;
+class Type;
+class Value;
 
 //===----------------------------------------------------------------------===//
 //                                AllocaInst Class
diff --git a/llvm/include/llvm/IR/IntrinsicInst.h b/llvm/include/llvm/IR/IntrinsicInst.h
index 05652204c281d9..959cbbdb1d4036 100644
--- a/llvm/include/llvm/IR/IntrinsicInst.h
+++ b/llvm/include/llvm/IR/IntrinsicInst.h
@@ -31,7 +31,6 @@
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/Metadata.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Casting.h"
 #include <cassert>
@@ -39,6 +38,8 @@
 
 namespace llvm {
 
+class Metadata;
+
 /// A wrapper class for inspecting calls to intrinsic functions.
 /// This allows the standard isa/dyncast/cast functionality to work with calls
 /// to intrinsic functions.
diff --git a/llvm/lib/Analysis/DomTreeUpdater.cpp b/llvm/lib/Analysis/DomTreeUpdater.cpp
index 6e299263e66da2..6b9376543b1a96 100644
--- a/llvm/lib/Analysis/DomTreeUpdater.cpp
+++ b/llvm/lib/Analysis/DomTreeUpdater.cpp
@@ -14,6 +14,7 @@
 #include "llvm/Analysis/DomTreeUpdater.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/Analysis/PostDominators.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/Support/GenericDomTree.h"
 #include <algorithm>
diff --git a/llvm/lib/CodeGen/MachineModuleInfo.cpp b/llvm/lib/CodeGen/MachineModuleInfo.cpp
index 31d4fc7d02bf17..a50de508449439 100644
--- a/llvm/lib/CodeGen/MachineModuleInfo.cpp
+++ b/llvm/lib/CodeGen/MachineModuleInfo.cpp
@@ -15,6 +15,7 @@
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/Instructions.h"
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index c9d3e473062b16..95676530a54ceb 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -55,6 +55,7 @@
 #include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instructions.h"
diff --git a/llvm/lib/IR/ReplaceConstant.cpp b/llvm/lib/IR/ReplaceConstant.cpp
index d2f676192e7fc9..069da26e63b121 100644
--- a/llvm/lib/IR/ReplaceConstant.cpp
+++ b/llvm/lib/IR/ReplaceConstant.cpp
@@ -13,6 +13,7 @@
 
 #include "llvm/IR/ReplaceConstant.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/ValueMap.h"
 
diff --git a/llvm/lib/Passes/StandardInstrumentations.cpp b/llvm/lib/Passes/StandardInstrumentations.cpp
index 5861c59175dd61..a8d6578793b391 100644
--- a/llvm/lib/Passes/StandardInstrumentations.cpp
+++ b/llvm/lib/Passes/StandardInstrumentations.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Analysis/CallGraphSCCPass.h"
 #include "llvm/Analysis/LazyCallGraph.h"
 #include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Module.h"
diff --git a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
index 6950675c5d5365..7d08f073fd81d5 100644
--- a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
@@ -15,8 +15,9 @@
 
 #include "AArch64MachineFunctionInfo.h"
 #include "AArch64InstrInfo.h"
-#include <llvm/IR/Metadata.h>
-#include <llvm/IR/Module.h>
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
 
 using namespace llvm;
 
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUOpenCLEnqueuedBlockLowering.cpp b/llvm/lib/Target/AMDGPU/AMDGPUOpenCLEnqueuedBlockLowering.cpp
index 3ddfab1b670ec1..fb7709d66c7610 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUOpenCLEnqueuedBlockLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUOpenCLEnqueuedBlockLowering.cpp
@@ -34,6 +34,7 @@
 #include "AMDGPU.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Mangler.h"
 #include "llvm/IR/Module.h"
diff --git a/llvm/lib/Transforms/IPO/CalledValuePropagation.cpp b/llvm/lib/Transforms/IPO/CalledValuePropagation.cpp
index 927dceec8865bb..ec5d578eb82773 100644
--- a/llvm/lib/Transforms/IPO/CalledValuePropagation.cpp
+++ b/llvm/lib/Transforms/IPO/CalledValuePropagation.cpp
@@ -19,11 +19,13 @@
 #include "llvm/Transforms/IPO/CalledValuePropagation.h"
 #include "llvm/Analysis/SparsePropagation.h"
 #include "llvm/Analysis/ValueLatticeUtils.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Transforms/IPO.h"
+
 using namespace llvm;
 
 #define DEBUG_TYPE "called-value-propagation"
diff --git a/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp b/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp
index ac3839f2a4ab57..a5cdb583cef09e 100644
--- a/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp
+++ b/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp
@@ -14,6 +14,7 @@
 
 #include "llvm/Transforms/Utils/CallGraphUpdater.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 
 using namespace llvm;
diff --git a/llvm/lib/Transforms/Utils/UnifyLoopExits.cpp b/llvm/lib/Transforms/Utils/UnifyLoopExits.cpp
index 0b718ed6136ea2..036c29b4ee266a 100644
--- a/llvm/lib/Transforms/Utils/UnifyLoopExits.cpp
+++ b/llvm/lib/Transforms/Utils/UnifyLoopExits.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Transforms/Utils/UnifyLoopExits.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Transforms/Utils.h"
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceArguments.cpp b/llvm/tools/llvm-reduce/deltas/ReduceArguments.cpp
index 04ac47ebc4a764..c9def7ee35547a 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceArguments.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceArguments.cpp
@@ -14,6 +14,7 @@
 #include "ReduceArguments.h"
 #include "Delta.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Intrinsics.h"
 #include <set>
 #include <vector>
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.cpp b/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.cpp
index c76322b2553727..b51891c883457a 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.cpp
@@ -14,6 +14,7 @@
 #include "ReduceBasicBlocks.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceFunctions.cpp b/llvm/tools/llvm-reduce/deltas/ReduceFunctions.cpp
index 2a26d4340af830..53f5b7d3fcec23 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceFunctions.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceFunctions.cpp
@@ -15,6 +15,7 @@
 #include "ReduceFunctions.h"
 #include "Delta.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
 #include <iterator>
 #include <vector>
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp b/llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp
index f27959fb98af51..692d7c2e9385d3 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "ReduceInstructions.h"
+#include "llvm/IR/Constants.h"
 
 using namespace llvm;
 
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp b/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp
index f1dcf24c6ea72f..04099ba3cd3c4e 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp
@@ -9,6 +9,7 @@
 #include "ReduceOperandsToArgs.h"
 #include "Delta.h"
 #include "llvm/ADT/Sequence.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instructions.h"