diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -121,6 +121,7 @@
 class Stmt;
 class StoredDeclsMap;
 class TargetAttr;
+class TargetInfo;
 class TemplateDecl;
 class TemplateParameterList;
 class TemplateTemplateParmDecl;
@@ -881,7 +882,7 @@
   void addedLocalImportDecl(ImportDecl *Import);
 
   static ImportDecl *getNextLocalImport(ImportDecl *Import) {
-    return Import->NextLocalImport;
+    return Import->getNextLocalImport();
   }
 
   using import_range = llvm::iterator_range<import_iterator>;
@@ -909,13 +910,7 @@
 
   /// Get the additional modules in which the definition \p Def has
   /// been merged.
-  ArrayRef<Module*> getModulesWithMergedDefinition(const NamedDecl *Def) {
-    auto MergedIt =
-        MergedDefModules.find(cast<NamedDecl>(Def->getCanonicalDecl()));
-    if (MergedIt == MergedDefModules.end())
-      return None;
-    return MergedIt->second;
-  }
+  ArrayRef<Module*> getModulesWithMergedDefinition(const NamedDecl *Def);
 
   /// Add a declaration to the list of declarations that are initialized
   /// for a module. This will typically be a global variable (with internal
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -4340,17 +4340,18 @@
   friend class ASTReader;
   friend TrailingObjects;
 
-  /// The imported module, along with a bit that indicates whether
-  /// we have source-location information for each identifier in the module
-  /// name.
-  ///
-  /// When the bit is false, we only have a single source location for the
-  /// end of the import declaration.
-  llvm::PointerIntPair<Module *, 1, bool> ImportedAndComplete;
+  /// The imported module.
+  Module *ImportedModule = nullptr;
 
   /// The next import in the list of imports local to the translation
   /// unit being parsed (not loaded from an AST file).
-  ImportDecl *NextLocalImport = nullptr;
+  ///
+  /// Includes a bit that indicates whether we have source-location information
+  /// for each identifier in the module name.
+  ///
+  /// When the bit is false, we only have a single source location for the
+  /// end of the import declaration.
+  llvm::PointerIntPair<ImportDecl *, 1, bool> NextLocalImportAndComplete;
 
   ImportDecl(DeclContext *DC, SourceLocation StartLoc, Module *Imported,
              ArrayRef<SourceLocation> IdentifierLocs);
@@ -4360,6 +4361,20 @@
 
   ImportDecl(EmptyShell Empty) : Decl(Import, Empty) {}
 
+  bool isImportComplete() const { return NextLocalImportAndComplete.getInt(); }
+
+  void setImportComplete(bool C) { NextLocalImportAndComplete.setInt(C); }
+
+  /// The next import in the list of imports local to the translation
+  /// unit being parsed (not loaded from an AST file).
+  ImportDecl *getNextLocalImport() const {
+    return NextLocalImportAndComplete.getPointer();
+  }
+
+  void setNextLocalImport(ImportDecl *Import) {
+    NextLocalImportAndComplete.setPointer(Import);
+  }
+
 public:
   /// Create a new module import declaration.
   static ImportDecl *Create(ASTContext &C, DeclContext *DC,
@@ -4377,7 +4392,7 @@
                                         unsigned NumLocations);
 
   /// Retrieve the module that was imported by the import declaration.
-  Module *getImportedModule() const { return ImportedAndComplete.getPointer(); }
+  Module *getImportedModule() const { return ImportedModule; }
 
   /// Retrieves the locations of each of the identifiers that make up
   /// the complete module name in the import declaration.
diff --git a/clang/include/clang/AST/ExternalASTSource.h b/clang/include/clang/AST/ExternalASTSource.h
--- a/clang/include/clang/AST/ExternalASTSource.h
+++ b/clang/include/clang/AST/ExternalASTSource.h
@@ -17,7 +17,6 @@
 #include "clang/AST/CharUnits.h"
 #include "clang/AST/DeclBase.h"
 #include "clang/Basic/LLVM.h"
-#include "clang/Basic/Module.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
@@ -39,6 +38,7 @@
 
 class ASTConsumer;
 class ASTContext;
+class ASTSourceDescriptor;
 class CXXBaseSpecifier;
 class CXXCtorInitializer;
 class CXXRecordDecl;
@@ -165,31 +165,6 @@
   /// object file.
   virtual bool DeclIsFromPCHWithObjectFile(const Decl *D) { return false; }
 
-  /// Abstracts clang modules and precompiled header files and holds
-  /// everything needed to generate debug info for an imported module
-  /// or PCH.
-  class ASTSourceDescriptor {
-    StringRef PCHModuleName;
-    StringRef Path;
-    StringRef ASTFile;
-    ASTFileSignature Signature;
-    const Module *ClangModule = nullptr;
-
-  public:
-    ASTSourceDescriptor() = default;
-    ASTSourceDescriptor(StringRef Name, StringRef Path, StringRef ASTFile,
-                        ASTFileSignature Signature)
-        : PCHModuleName(std::move(Name)), Path(std::move(Path)),
-          ASTFile(std::move(ASTFile)), Signature(Signature) {}
-    ASTSourceDescriptor(const Module &M);
-
-    std::string getModuleName() const;
-    StringRef getPath() const { return Path; }
-    StringRef getASTFile() const { return ASTFile; }
-    ASTFileSignature getSignature() const { return Signature; }
-    const Module *getModuleOrNull() const { return ClangModule; }
-  };
-
   /// Return a descriptor for the corresponding module, if one exists.
   virtual llvm::Optional<ASTSourceDescriptor> getSourceDescriptor(unsigned ID);
 
diff --git a/clang/include/clang/Basic/Module.h b/clang/include/clang/Basic/Module.h
--- a/clang/include/clang/Basic/Module.h
+++ b/clang/include/clang/Basic/Module.h
@@ -654,6 +654,32 @@
   unsigned Generation = 0;
 };
 
+/// Abstracts clang modules and precompiled header files and holds
+/// everything needed to generate debug info for an imported module
+/// or PCH.
+class ASTSourceDescriptor {
+  StringRef PCHModuleName;
+  StringRef Path;
+  StringRef ASTFile;
+  ASTFileSignature Signature;
+  const Module *ClangModule = nullptr;
+
+public:
+  ASTSourceDescriptor() = default;
+  ASTSourceDescriptor(StringRef Name, StringRef Path, StringRef ASTFile,
+                      ASTFileSignature Signature)
+      : PCHModuleName(std::move(Name)), Path(std::move(Path)),
+        ASTFile(std::move(ASTFile)), Signature(Signature) {}
+  ASTSourceDescriptor(const Module &M);
+
+  std::string getModuleName() const;
+  StringRef getPath() const { return Path; }
+  StringRef getASTFile() const { return ASTFile; }
+  ASTFileSignature getSignature() const { return Signature; }
+  const Module *getModuleOrNull() const { return ClangModule; }
+};
+
+
 } // namespace clang
 
 #endif // LLVM_CLANG_BASIC_MODULE_H
diff --git a/clang/include/clang/StaticAnalyzer/Frontend/CheckerRegistry.h b/clang/include/clang/StaticAnalyzer/Frontend/CheckerRegistry.h
--- a/clang/include/clang/StaticAnalyzer/Frontend/CheckerRegistry.h
+++ b/clang/include/clang/StaticAnalyzer/Frontend/CheckerRegistry.h
@@ -13,6 +13,7 @@
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/SetVector.h"
 #include <cstddef>
 #include <vector>
 
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -55,6 +55,7 @@
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/Linkage.h"
+#include "clang/Basic/Module.h"
 #include "clang/Basic/ObjCRuntime.h"
 #include "clang/Basic/SanitizerBlacklist.h"
 #include "clang/Basic/SourceLocation.h"
@@ -1103,6 +1104,15 @@
   Merged.erase(std::remove(Merged.begin(), Merged.end(), nullptr), Merged.end());
 }
 
+ArrayRef<Module *>
+ASTContext::getModulesWithMergedDefinition(const NamedDecl *Def) {
+  auto MergedIt =
+      MergedDefModules.find(cast<NamedDecl>(Def->getCanonicalDecl()));
+  if (MergedIt == MergedDefModules.end())
+    return None;
+  return MergedIt->second;
+}
+
 void ASTContext::PerModuleInitializers::resolve(ASTContext &Ctx) {
   if (LazyInitializers.empty())
     return;
@@ -1606,7 +1616,7 @@
 }
 
 void ASTContext::addedLocalImportDecl(ImportDecl *Import) {
-  assert(!Import->NextLocalImport && "Import declaration already in the chain");
+  assert(!Import->getNextLocalImport() && "Import declaration already in the chain");
   assert(!Import->isFromASTFile() && "Non-local import declaration");
   if (!FirstLocalImport) {
     FirstLocalImport = Import;
@@ -1614,7 +1624,7 @@
     return;
   }
 
-  LastLocalImport->NextLocalImport = Import;
+  LastLocalImport->setNextLocalImport(Import);
   LastLocalImport = Import;
 }
 
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4896,7 +4896,8 @@
 ImportDecl::ImportDecl(DeclContext *DC, SourceLocation StartLoc,
                        Module *Imported,
                        ArrayRef<SourceLocation> IdentifierLocs)
-  : Decl(Import, DC, StartLoc), ImportedAndComplete(Imported, true) {
+    : Decl(Import, DC, StartLoc), ImportedModule(Imported),
+      NextLocalImportAndComplete(nullptr, true) {
   assert(getNumModuleIdentifiers(Imported) == IdentifierLocs.size());
   auto *StoredLocs = getTrailingObjects<SourceLocation>();
   std::uninitialized_copy(IdentifierLocs.begin(), IdentifierLocs.end(),
@@ -4905,7 +4906,8 @@
 
 ImportDecl::ImportDecl(DeclContext *DC, SourceLocation StartLoc,
                        Module *Imported, SourceLocation EndLoc)
-  : Decl(Import, DC, StartLoc), ImportedAndComplete(Imported, false) {
+    : Decl(Import, DC, StartLoc), ImportedModule(Imported),
+      NextLocalImportAndComplete(nullptr, false) {
   *getTrailingObjects<SourceLocation>() = EndLoc;
 }
 
@@ -4934,7 +4936,7 @@
 }
 
 ArrayRef<SourceLocation> ImportDecl::getIdentifierLocs() const {
-  if (!ImportedAndComplete.getInt())
+  if (!isImportComplete())
     return None;
 
   const auto *StoredLocs = getTrailingObjects<SourceLocation>();
@@ -4943,7 +4945,7 @@
 }
 
 SourceRange ImportDecl::getSourceRange() const {
-  if (!ImportedAndComplete.getInt())
+  if (!isImportComplete())
     return SourceRange(getLocation(), *getTrailingObjects<SourceLocation>());
 
   return SourceRange(getLocation(), getIdentifierLocs().back());
diff --git a/clang/lib/AST/ExternalASTSource.cpp b/clang/lib/AST/ExternalASTSource.cpp
--- a/clang/lib/AST/ExternalASTSource.cpp
+++ b/clang/lib/AST/ExternalASTSource.cpp
@@ -29,7 +29,7 @@
 
 ExternalASTSource::~ExternalASTSource() = default;
 
-llvm::Optional<ExternalASTSource::ASTSourceDescriptor>
+llvm::Optional<ASTSourceDescriptor>
 ExternalASTSource::getSourceDescriptor(unsigned ID) {
   return None;
 }
@@ -39,21 +39,6 @@
   return EK_ReplyHazy;
 }
 
-ExternalASTSource::ASTSourceDescriptor::ASTSourceDescriptor(const Module &M)
-  : Signature(M.Signature), ClangModule(&M) {
-  if (M.Directory)
-    Path = M.Directory->getName();
-  if (auto *File = M.getASTFile())
-    ASTFile = File->getName();
-}
-
-std::string ExternalASTSource::ASTSourceDescriptor::getModuleName() const {
-  if (ClangModule)
-    return ClangModule->Name;
-  else
-    return std::string(PCHModuleName);
-}
-
 void ExternalASTSource::FindFileRegionDecls(FileID File, unsigned Offset,
                                             unsigned Length,
                                             SmallVectorImpl<Decl *> &Decls) {}
diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -13,6 +13,7 @@
 //   http://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling
 //
 //===----------------------------------------------------------------------===//
+
 #include "clang/AST/Mangle.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attr.h"
@@ -27,6 +28,7 @@
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/ABI.h"
+#include "clang/Basic/Module.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/StringExtras.h"
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -15,6 +15,7 @@
 #include "clang/AST/DeclOpenMP.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/LocInfoType.h"
+#include "clang/Basic/Module.h"
 #include "clang/Basic/SourceManager.h"
 
 using namespace clang;
diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -658,3 +658,18 @@
   };
   VisitModule({M, nullptr});
 }
+
+ASTSourceDescriptor::ASTSourceDescriptor(const Module &M)
+    : Signature(M.Signature), ClangModule(&M) {
+  if (M.Directory)
+    Path = M.Directory->getName();
+  if (auto *File = M.getASTFile())
+    ASTFile = File->getName();
+}
+
+std::string ASTSourceDescriptor::getModuleName() const {
+  if (ClangModule)
+    return ClangModule->Name;
+  else
+    return std::string(PCHModuleName);
+}
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -20,6 +20,7 @@
 #include "clang/AST/Type.h"
 #include "clang/AST/TypeOrdering.h"
 #include "clang/Basic/CodeGenOptions.h"
+#include "clang/Basic/Module.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
@@ -60,7 +61,7 @@
   llvm::DIBuilder DBuilder;
   llvm::DICompileUnit *TheCU = nullptr;
   ModuleMap *ClangModuleMap = nullptr;
-  ExternalASTSource::ASTSourceDescriptor PCHDescriptor;
+  ASTSourceDescriptor PCHDescriptor;
   SourceLocation CurLoc;
   llvm::MDNode *CurInlinedAt = nullptr;
   llvm::DIType *VTablePtrType = nullptr;
@@ -379,9 +380,7 @@
   /// When generating debug information for a clang module or
   /// precompiled header, this module map will be used to determine
   /// the module of origin of each Decl.
-  void setPCHDescriptor(ExternalASTSource::ASTSourceDescriptor PCH) {
-    PCHDescriptor = PCH;
-  }
+  void setPCHDescriptor(ASTSourceDescriptor PCH) { PCHDescriptor = PCH; }
   /// @}
 
   /// Update the current source location. If \arg loc is invalid it is
@@ -590,9 +589,8 @@
 
   /// Get a reference to a clang module.  If \p CreateSkeletonCU is true,
   /// this also creates a split dwarf skeleton compile unit.
-  llvm::DIModule *
-  getOrCreateModuleRef(ExternalASTSource::ASTSourceDescriptor Mod,
-                       bool CreateSkeletonCU);
+  llvm::DIModule *getOrCreateModuleRef(ASTSourceDescriptor Mod,
+                                       bool CreateSkeletonCU);
 
   /// DebugTypeExtRefs: If \p D originated in a clang module, return it.
   llvm::DIModule *getParentModuleOrNull(const Decl *D);
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2431,9 +2431,8 @@
   return CreateTypeDefinition(Ty, Unit);
 }
 
-llvm::DIModule *
-CGDebugInfo::getOrCreateModuleRef(ExternalASTSource::ASTSourceDescriptor Mod,
-                                  bool CreateSkeletonCU) {
+llvm::DIModule *CGDebugInfo::getOrCreateModuleRef(ASTSourceDescriptor Mod,
+                                                  bool CreateSkeletonCU) {
   // Use the Module pointer as the key into the cache. This is a
   // nullptr if the "Module" is a PCH, which is safe because we don't
   // support chained PCH debug info, so there can only be a single PCH.
@@ -2498,9 +2497,8 @@
 
   llvm::DIModule *Parent =
       IsRootModule ? nullptr
-                   : getOrCreateModuleRef(
-                         ExternalASTSource::ASTSourceDescriptor(*M->Parent),
-                         CreateSkeletonCU);
+                   : getOrCreateModuleRef(ASTSourceDescriptor(*M->Parent),
+                                          CreateSkeletonCU);
   llvm::DIModule *DIMod =
       DBuilder.createModule(Parent, Mod.getModuleName(), ConfigMacros,
                             Mod.getPath());
@@ -3057,7 +3055,7 @@
     // option.
     if (Module *M = D->getOwningModule()) {
       // This is a (sub-)module.
-      auto Info = ExternalASTSource::ASTSourceDescriptor(*M);
+      auto Info = ASTSourceDescriptor(*M);
       return getOrCreateModuleRef(Info, /*SkeletonCU=*/false);
     } else {
       // This the precompiled header being built.
@@ -4715,7 +4713,7 @@
   if (CGM.getCodeGenOpts().getDebuggerTuning() != llvm::DebuggerKind::LLDB)
     return;
   if (Module *M = ID.getImportedModule()) {
-    auto Info = ExternalASTSource::ASTSourceDescriptor(*M);
+    auto Info = ASTSourceDescriptor(*M);
     auto Loc = ID.getLocation();
     DBuilder.createImportedDeclaration(
         getCurrentContextDescriptor(cast<Decl>(ID.getDeclContext())),
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -8491,10 +8491,10 @@
   return (I - PCHModules.end()) << 1;
 }
 
-llvm::Optional<ExternalASTSource::ASTSourceDescriptor>
+llvm::Optional<ASTSourceDescriptor>
 ASTReader::getSourceDescriptor(unsigned ID) {
   if (const Module *M = getSubmodule(ID))
-    return ExternalASTSource::ASTSourceDescriptor(*M);
+    return ASTSourceDescriptor(*M);
 
   // If there is only a single PCH, return it instead.
   // Chained PCH are not supported.
@@ -8503,8 +8503,8 @@
     ModuleFile &MF = ModuleMgr.getPrimaryModule();
     StringRef ModuleName = llvm::sys::path::filename(MF.OriginalSourceFileName);
     StringRef FileName = llvm::sys::path::filename(MF.FileName);
-    return ASTReader::ASTSourceDescriptor(ModuleName, MF.OriginalDir, FileName,
-                                          MF.Signature);
+    return ASTSourceDescriptor(ModuleName, MF.OriginalDir, FileName,
+                               MF.Signature);
   }
   return None;
 }
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1968,8 +1968,8 @@
 
 void ASTDeclReader::VisitImportDecl(ImportDecl *D) {
   VisitDecl(D);
-  D->ImportedAndComplete.setPointer(readModule());
-  D->ImportedAndComplete.setInt(Record.readInt());
+  D->ImportedModule = readModule();
+  D->setImportComplete(Record.readInt());
   auto *StoredLocs = D->getTrailingObjects<SourceLocation>();
   for (unsigned I = 0, N = Record.back(); I != N; ++I)
     StoredLocs[I] = readSourceLocation();
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.h b/lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.h
--- a/lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.h
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.h
@@ -9,6 +9,7 @@
 #ifndef LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_ASTUTILS_H
 #define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_ASTUTILS_H
 
+#include "clang/Basic/Module.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/MultiplexExternalSemaSource.h"
 #include "clang/Sema/Sema.h"
@@ -71,7 +72,7 @@
     return m_Source->getModule(ID);
   }
 
-  llvm::Optional<ASTSourceDescriptor>
+  llvm::Optional<clang::ASTSourceDescriptor>
   getSourceDescriptor(unsigned ID) override {
     return m_Source->getSourceDescriptor(ID);
   }
diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h
@@ -40,6 +40,10 @@
 class DWARFASTParserClang;
 class PDBASTParser;
 
+namespace clang {
+class FileManager;
+}
+
 namespace lldb_private {
 
 class ClangASTMetadata;