diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index 4a807773f2a4..b66009e909a1 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -28,6 +28,7 @@
 #include "clang/Basic/AddressSpaces.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/LangOptions.h"
+#include "clang/Basic/Module.h"
 #include "clang/Basic/OperatorKinds.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/SanitizerBlacklist.h"
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 1b4e3731e158..046ce70a343b 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -21,6 +21,7 @@
 #include "clang/AST/Redeclarable.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/Linkage.h"
+#include "clang/Basic/Module.h"
 #include "clang/Basic/OperatorKinds.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
@@ -38,7 +39,6 @@ class FunctionTemplateDecl;
 class FunctionTemplateSpecializationInfo;
 class LabelStmt;
 class MemberSpecializationInfo;
-class Module;
 class NestedNameSpecifier;
 class ParmVarDecl;
 class Stmt;
diff --git a/clang/include/clang/Basic/Module.h b/clang/include/clang/Basic/Module.h
index fa032e9eb669..1702fb1114d7 100644
--- a/clang/include/clang/Basic/Module.h
+++ b/clang/include/clang/Basic/Module.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_CLANG_BASIC_MODULE_H
 #define LLVM_CLANG_BASIC_MODULE_H
 
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseSet.h"
@@ -35,9 +36,6 @@ namespace llvm {
 
 namespace clang {
   
-class DirectoryEntry;
-class FileEntry;
-class FileManager;
 class LangOptions;
 class TargetInfo;
 class IdentifierInfo;
diff --git a/clang/include/clang/Serialization/Module.h b/clang/include/clang/Serialization/Module.h
index 3fdb33f495d6..d6d16a023044 100644
--- a/clang/include/clang/Serialization/Module.h
+++ b/clang/include/clang/Serialization/Module.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_CLANG_SERIALIZATION_MODULE_H
 #define LLVM_CLANG_SERIALIZATION_MODULE_H
 
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Serialization/ASTBitCodes.h"
 #include "clang/Serialization/ContinuousRangeMap.h"
@@ -32,7 +33,6 @@ template <typename Info> class OnDiskIterableChainedHashTable;
 
 namespace clang {
 
-class FileEntry;
 class DeclContext;
 class Module;
 
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h
index faa350004511..ce81c98c206b 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h
@@ -14,6 +14,7 @@
 #ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_FUNCTIONSUMMARY_H
 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_FUNCTIONSUMMARY_H
 
+#include "clang/AST/Decl.h"
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
@@ -22,7 +23,6 @@
 #include <deque>
 
 namespace clang {
-class Decl;
 
 namespace ento {
 typedef std::deque<Decl*> SetOfDecls;
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
index 77841ce64360..bb835c4c565e 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
@@ -19,6 +19,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/CharUnits.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 973445ca2a71..108677abb8a4 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -19,6 +19,7 @@
 #include "clang/AST/Comment.h"
 #include "clang/AST/CommentCommandTraits.h"
 #include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclContextInternals.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/Expr.h"
diff --git a/clang/lib/Frontend/InitHeaderSearch.cpp b/clang/lib/Frontend/InitHeaderSearch.cpp
index 3072751ad9c6..26bab0db5347 100644
--- a/clang/lib/Frontend/InitHeaderSearch.cpp
+++ b/clang/lib/Frontend/InitHeaderSearch.cpp
@@ -15,6 +15,7 @@
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Config/config.h" // C_INCLUDE_DIRS
+#include "clang/Lex/HeaderMap.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/HeaderSearchOptions.h"
 #include "llvm/ADT/SmallPtrSet.h"