diff --git a/clang/include/clang/Basic/FileEntry.h b/clang/include/clang/Basic/FileEntry.h
--- a/clang/include/clang/Basic/FileEntry.h
+++ b/clang/include/clang/Basic/FileEntry.h
@@ -64,6 +64,7 @@
   inline unsigned getUID() const;
   inline const llvm::sys::fs::UniqueID &getUniqueID() const;
   inline time_t getModificationTime() const;
+  inline void closeFile() const;
 
   /// Check if the underlying FileEntry is the same, intentially ignoring
   /// whether the file was referenced with the same spelling of the filename.
@@ -360,6 +361,8 @@
   return getFileEntry().getModificationTime();
 }
 
+void FileEntryRef::closeFile() const { getFileEntry().closeFile(); }
+
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_FILEENTRY_H
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
@@ -15,6 +15,7 @@
 #ifndef LLVM_CLANG_BASIC_MODULE_H
 #define LLVM_CLANG_BASIC_MODULE_H
 
+#include "clang/Basic/FileEntry.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseSet.h"
@@ -160,7 +161,7 @@
 
   /// The AST file if this is a top-level module which has a
   /// corresponding serialized AST file, or null otherwise.
-  const FileEntry *ASTFile = nullptr;
+  Optional<FileEntryRef> ASTFile;
 
   /// The top-level headers associated with this module.
   llvm::SmallSetVector<const FileEntry *, 2> TopHeaders;
@@ -529,14 +530,14 @@
   }
 
   /// The serialized AST file for this module, if one was created.
-  const FileEntry *getASTFile() const {
+  OptionalFileEntryRefDegradesToFileEntryPtr getASTFile() const {
     return getTopLevelModule()->ASTFile;
   }
 
   /// Set the serialized AST file for the top-level module of this module.
-  void setASTFile(const FileEntry *File) {
-    assert((File == nullptr || getASTFile() == nullptr ||
-            getASTFile() == File) && "file path changed");
+  void setASTFile(Optional<FileEntryRef> File) {
+    assert((!File || !getASTFile() || getASTFile() == File) &&
+           "file path changed");
     getTopLevelModule()->ASTFile = File;
   }
 
diff --git a/clang/include/clang/Serialization/ModuleFile.h b/clang/include/clang/Serialization/ModuleFile.h
--- a/clang/include/clang/Serialization/ModuleFile.h
+++ b/clang/include/clang/Serialization/ModuleFile.h
@@ -159,7 +159,7 @@
   bool DidReadTopLevelSubmodule = false;
 
   /// The file entry for the module file.
-  const FileEntry *File = nullptr;
+  OptionalFileEntryRefDegradesToFileEntryPtr File;
 
   /// The signature of the module file, which may be used instead of the size
   /// and modification time to identify this particular file.
diff --git a/clang/include/clang/Serialization/ModuleManager.h b/clang/include/clang/Serialization/ModuleManager.h
--- a/clang/include/clang/Serialization/ModuleManager.h
+++ b/clang/include/clang/Serialization/ModuleManager.h
@@ -307,10 +307,8 @@
   /// \returns True if a file exists but does not meet the size/
   /// modification time criteria, false if the file is either available and
   /// suitable, or is missing.
-  bool lookupModuleFile(StringRef FileName,
-                        off_t ExpectedSize,
-                        time_t ExpectedModTime,
-                        const FileEntry *&File);
+  bool lookupModuleFile(StringRef FileName, off_t ExpectedSize,
+                        time_t ExpectedModTime, Optional<FileEntryRef> &File);
 
   /// View the graphviz representation of the module graph.
   void viewGraph();
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
@@ -671,7 +671,7 @@
     : Signature(M.Signature), ClangModule(&M) {
   if (M.Directory)
     Path = M.Directory->getName();
-  if (auto *File = M.getASTFile())
+  if (auto File = M.getASTFile())
     ASTFile = File->getName();
 }
 
diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -187,7 +187,7 @@
       Diag(Path[0].second, diag::err_module_redefinition) << ModuleName;
       if (M->DefinitionLoc.isValid())
         Diag(M->DefinitionLoc, diag::note_prev_module_definition);
-      else if (const auto *FE = M->getASTFile())
+      else if (Optional<FileEntryRef> FE = M->getASTFile())
         Diag(M->DefinitionLoc, diag::note_prev_module_definition_from_ast_file)
             << FE->getName();
       Mod = M;
diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp
--- a/clang/lib/Serialization/ModuleManager.cpp
+++ b/clang/lib/Serialization/ModuleManager.cpp
@@ -112,7 +112,7 @@
 
   // Look for the file entry. This only fails if the expected size or
   // modification time differ.
-  const FileEntry *Entry;
+  OptionalFileEntryRefDegradesToFileEntryPtr Entry;
   if (Type == MK_ExplicitModule || Type == MK_PrebuiltModule) {
     // If we're not expecting to pull this file out of the module cache, it
     // might have a different mtime due to being moved across filesystems in
@@ -288,7 +288,7 @@
     if (modMap) {
       StringRef ModuleName = victim->ModuleName;
       if (Module *mod = modMap->findModule(ModuleName)) {
-        mod->setASTFile(nullptr);
+        mod->setASTFile(None);
       }
     }
   }
@@ -458,18 +458,18 @@
   returnVisitState(State);
 }
 
-bool ModuleManager::lookupModuleFile(StringRef FileName,
-                                     off_t ExpectedSize,
+bool ModuleManager::lookupModuleFile(StringRef FileName, off_t ExpectedSize,
                                      time_t ExpectedModTime,
-                                     const FileEntry *&File) {
-  File = nullptr;
+                                     Optional<FileEntryRef> &File) {
+  File = None;
   if (FileName == "-")
     return false;
 
   // Open the file immediately to ensure there is no race between stat'ing and
   // opening the file.
-  auto FileOrErr = FileMgr.getFile(FileName, /*OpenFile=*/true,
-                                   /*CacheFailure=*/false);
+  Optional<FileEntryRef> FileOrErr =
+      expectedToOptional(FileMgr.getFileRef(FileName, /*OpenFile=*/true,
+                                            /*CacheFailure=*/false));
   if (!FileOrErr)
     return false;
 
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -8400,7 +8400,9 @@
   if (!CXMod)
     return nullptr;
   Module *Mod = static_cast<Module *>(CXMod);
-  return const_cast<FileEntry *>(Mod->getASTFile());
+  if (auto File = Mod->getASTFile())
+    return const_cast<FileEntry *>(&File->getFileEntry());
+  return nullptr;
 }
 
 CXModule clang_Module_getParent(CXModule CXMod) {
diff --git a/clang/tools/libclang/CXIndexDataConsumer.cpp b/clang/tools/libclang/CXIndexDataConsumer.cpp
--- a/clang/tools/libclang/CXIndexDataConsumer.cpp
+++ b/clang/tools/libclang/CXIndexDataConsumer.cpp
@@ -491,13 +491,12 @@
     if (SrcMod->getTopLevelModule() == Mod->getTopLevelModule())
       return;
 
-  CXIdxImportedASTFileInfo Info = {
-                                    static_cast<CXFile>(
-                                    const_cast<FileEntry *>(Mod->getASTFile())),
-                                    Mod,
-                                    getIndexLoc(ImportD->getLocation()),
-                                    ImportD->isImplicit()
-                                  };
+  FileEntry *FE = nullptr;
+  if (auto File = Mod->getASTFile())
+    FE = const_cast<FileEntry *>(&File->getFileEntry());
+  CXIdxImportedASTFileInfo Info = {static_cast<CXFile>(FE), Mod,
+                                   getIndexLoc(ImportD->getLocation()),
+                                   ImportD->isImplicit()};
   CXIdxClientASTFile astFile = CB.importedASTFile(ClientData, &Info);
   (void)astFile;
 }