diff --git a/llvm/tools/dsymutil/Reproducer.h b/llvm/tools/dsymutil/Reproducer.h
--- a/llvm/tools/dsymutil/Reproducer.h
+++ b/llvm/tools/dsymutil/Reproducer.h
@@ -9,7 +9,6 @@
 #ifndef LLVM_TOOLS_DSYMUTIL_REPRODUCER_H
 #define LLVM_TOOLS_DSYMUTIL_REPRODUCER_H
 
-#include "llvm/Support/Error.h"
 #include "llvm/Support/FileCollector.h"
 #include "llvm/Support/VirtualFileSystem.h"
 
diff --git a/llvm/tools/llvm-exegesis/lib/PerfHelper.h b/llvm/tools/llvm-exegesis/lib/PerfHelper.h
--- a/llvm/tools/llvm-exegesis/lib/PerfHelper.h
+++ b/llvm/tools/llvm-exegesis/lib/PerfHelper.h
@@ -14,7 +14,6 @@
 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H
 #define LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H
 
-#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Config/config.h"
diff --git a/llvm/tools/llvm-ifs/ErrorCollector.h b/llvm/tools/llvm-ifs/ErrorCollector.h
--- a/llvm/tools/llvm-ifs/ErrorCollector.h
+++ b/llvm/tools/llvm-ifs/ErrorCollector.h
@@ -21,10 +21,13 @@
 #ifndef LLVM_TOOLS_LLVM_IFS_ERRORCOLLECTOR_H
 #define LLVM_TOOLS_LLVM_IFS_ERRORCOLLECTOR_H
 
-#include "llvm/Support/Error.h"
+#include "llvm/Support/raw_ostream.h"
 #include <vector>
 
 namespace llvm {
+
+class Error;
+
 namespace ifs {
 
 class ErrorCollector {
diff --git a/llvm/tools/llvm-mca/Views/InstructionView.h b/llvm/tools/llvm-mca/Views/InstructionView.h
--- a/llvm/tools/llvm-mca/Views/InstructionView.h
+++ b/llvm/tools/llvm-mca/Views/InstructionView.h
@@ -17,9 +17,10 @@
 
 #include "llvm/MCA/View.h"
 #include "llvm/Support/JSON.h"
-#include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
+class MCInstPrinter;
+
 namespace mca {
 
 // The base class for views that deal with individual machine instructions.
diff --git a/llvm/tools/llvm-pdbutil/OutputStyle.h b/llvm/tools/llvm-pdbutil/OutputStyle.h
--- a/llvm/tools/llvm-pdbutil/OutputStyle.h
+++ b/llvm/tools/llvm-pdbutil/OutputStyle.h
@@ -9,9 +9,10 @@
 #ifndef LLVM_TOOLS_LLVMPDBDUMP_OUTPUTSTYLE_H
 #define LLVM_TOOLS_LLVMPDBDUMP_OUTPUTSTYLE_H
 
-#include "llvm/Support/Error.h"
-
 namespace llvm {
+
+class Error;
+
 namespace pdb {
 
 class OutputStyle {
diff --git a/llvm/tools/llvm-reduce/DeltaManager.cpp b/llvm/tools/llvm-reduce/DeltaManager.cpp
--- a/llvm/tools/llvm-reduce/DeltaManager.cpp
+++ b/llvm/tools/llvm-reduce/DeltaManager.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "DeltaManager.h"
+#include "ReducerWorkItem.h"
 #include "TestRunner.h"
 #include "deltas/Delta.h"
 #include "deltas/ReduceAliases.h"
diff --git a/llvm/tools/llvm-reduce/ReducerWorkItem.cpp b/llvm/tools/llvm-reduce/ReducerWorkItem.cpp
--- a/llvm/tools/llvm-reduce/ReducerWorkItem.cpp
+++ b/llvm/tools/llvm-reduce/ReducerWorkItem.cpp
@@ -14,6 +14,7 @@
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/TargetInstrInfo.h"
 #include "llvm/IR/Verifier.h"
diff --git a/llvm/tools/llvm-reduce/TestRunner.h b/llvm/tools/llvm-reduce/TestRunner.h
--- a/llvm/tools/llvm-reduce/TestRunner.h
+++ b/llvm/tools/llvm-reduce/TestRunner.h
@@ -37,10 +37,7 @@
   /// Returns the most reduced version of the original testcase
   ReducerWorkItem &getProgram() const { return *Program; }
 
-  void setProgram(std::unique_ptr<ReducerWorkItem> P) {
-    assert(P && "Setting null program?");
-    Program = std::move(P);
-  }
+  void setProgram(std::unique_ptr<ReducerWorkItem> P);
 
   const TargetMachine *getTargetMachine() const { return TM.get(); }
 
diff --git a/llvm/tools/llvm-reduce/TestRunner.cpp b/llvm/tools/llvm-reduce/TestRunner.cpp
--- a/llvm/tools/llvm-reduce/TestRunner.cpp
+++ b/llvm/tools/llvm-reduce/TestRunner.cpp
@@ -7,6 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "TestRunner.h"
+#include "ReducerWorkItem.h"
+#include "llvm/CodeGen/MachineFunction.h"
 
 using namespace llvm;
 
@@ -45,3 +47,8 @@
 
   return !Result;
 }
+
+void TestRunner::setProgram(std::unique_ptr<ReducerWorkItem> P) {
+  assert(P && "Setting null program?");
+  Program = std::move(P);
+}
diff --git a/llvm/tools/llvm-reduce/deltas/Delta.h b/llvm/tools/llvm-reduce/deltas/Delta.h
--- a/llvm/tools/llvm-reduce/deltas/Delta.h
+++ b/llvm/tools/llvm-reduce/deltas/Delta.h
@@ -23,6 +23,8 @@
 
 namespace llvm {
 
+class MachineFunction;
+
 struct Chunk {
   int Begin;
   int End;
diff --git a/llvm/tools/llvm-reduce/deltas/Delta.cpp b/llvm/tools/llvm-reduce/deltas/Delta.cpp
--- a/llvm/tools/llvm-reduce/deltas/Delta.cpp
+++ b/llvm/tools/llvm-reduce/deltas/Delta.cpp
@@ -17,6 +17,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
+#include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ThreadPool.h"
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.cpp b/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.cpp
--- a/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.cpp
@@ -14,6 +14,7 @@
 #include "ReduceInstructionsMIR.h"
 #include "Delta.h"
 
+#include "llvm/ADT/SetVector.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
diff --git a/llvm/tools/llvm-reduce/llvm-reduce.cpp b/llvm/tools/llvm-reduce/llvm-reduce.cpp
--- a/llvm/tools/llvm-reduce/llvm-reduce.cpp
+++ b/llvm/tools/llvm-reduce/llvm-reduce.cpp
@@ -19,6 +19,8 @@
 #include "TestRunner.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/CodeGen/CommandFlags.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/IRReader/IRReader.h"
diff --git a/llvm/tools/opt/NewPMDriver.h b/llvm/tools/opt/NewPMDriver.h
--- a/llvm/tools/opt/NewPMDriver.h
+++ b/llvm/tools/opt/NewPMDriver.h
@@ -20,7 +20,6 @@
 #ifndef LLVM_TOOLS_OPT_NEWPMDRIVER_H
 #define LLVM_TOOLS_OPT_NEWPMDRIVER_H
 
-#include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/CommandLine.h"
 
 namespace llvm {