Index: clang/include/clang/Basic/SourceManager.h
===================================================================
--- clang/include/clang/Basic/SourceManager.h
+++ clang/include/clang/Basic/SourceManager.h
@@ -1840,7 +1840,7 @@
                           SrcMgr::CharacteristicKind DirCharacter, int LoadedID,
                           unsigned LoadedOffset);
 
-  SrcMgr::ContentCache &getOrCreateContentCache(const FileEntry *SourceFile,
+  SrcMgr::ContentCache &getOrCreateContentCache(FileEntryRef SourceFile,
                                                 bool isSystemFile = false);
 
   /// Create a new ContentCache for the specified  memory buffer.
Index: clang/lib/Basic/SourceManager.cpp
===================================================================
--- clang/lib/Basic/SourceManager.cpp
+++ clang/lib/Basic/SourceManager.cpp
@@ -380,10 +380,8 @@
   }
 }
 
-ContentCache &SourceManager::getOrCreateContentCache(const FileEntry *FileEnt,
+ContentCache &SourceManager::getOrCreateContentCache(FileEntryRef FileEnt,
                                                      bool isSystemFile) {
-  assert(FileEnt && "Didn't specify a file entry to use?");
-
   // Do we already have information about this file?
   ContentCache *&Entry = FileInfos[FileEnt];
   if (Entry)
@@ -528,7 +526,7 @@
                                    SourceLocation IncludePos,
                                    SrcMgr::CharacteristicKind FileCharacter,
                                    int LoadedID, unsigned LoadedOffset) {
-  SrcMgr::ContentCache &IR = getOrCreateContentCache(&SourceFile.getFileEntry(),
+  SrcMgr::ContentCache &IR = getOrCreateContentCache(SourceFile,
                                                      isSystem(FileCharacter));
   return createFileIDImpl(IR, SourceFile.getName(), IncludePos, FileCharacter,
                           LoadedID, LoadedOffset);
@@ -662,13 +660,13 @@
 
 llvm::Optional<llvm::MemoryBufferRef>
 SourceManager::getMemoryBufferForFileOrNone(const FileEntry *File) {
-  SrcMgr::ContentCache &IR = getOrCreateContentCache(File);
+  SrcMgr::ContentCache &IR = getOrCreateContentCache(File->getLastRef());
   return IR.getBufferOrNone(Diag, getFileManager(), SourceLocation());
 }
 
 void SourceManager::overrideFileContents(
     const FileEntry *SourceFile, std::unique_ptr<llvm::MemoryBuffer> Buffer) {
-  SrcMgr::ContentCache &IR = getOrCreateContentCache(SourceFile);
+  SrcMgr::ContentCache &IR = getOrCreateContentCache(SourceFile->getLastRef());
 
   IR.setBuffer(std::move(Buffer));
   IR.BufferOverridden = true;
@@ -696,12 +694,12 @@
   if (!BypassFile)
     return None;
 
-  (void)getOrCreateContentCache(&BypassFile->getFileEntry());
+  (void)getOrCreateContentCache(*BypassFile);
   return BypassFile;
 }
 
 void SourceManager::setFileIsTransient(const FileEntry *File) {
-  getOrCreateContentCache(File).IsTransient = true;
+  getOrCreateContentCache(File->getLastRef()).IsTransient = true;
 }
 
 Optional<StringRef>
Index: clang/lib/Serialization/ASTReader.cpp
===================================================================
--- clang/lib/Serialization/ASTReader.cpp
+++ clang/lib/Serialization/ASTReader.cpp
@@ -1499,7 +1499,7 @@
     // we will also try to fail gracefully by setting up the SLocEntry.
     unsigned InputID = Record[4];
     InputFile IF = getInputFile(*F, InputID);
-    const FileEntry *File = IF.getFile();
+    Optional<FileEntryRef> File = IF.getFile();
     bool OverriddenBuffer = IF.isOverridden();
 
     // Note that we only check if a File was returned. If it was out-of-date
@@ -1516,7 +1516,7 @@
     SrcMgr::CharacteristicKind
       FileCharacter = (SrcMgr::CharacteristicKind)Record[2];
     // FIXME: The FileID should be created from the FileEntryRef.
-    FileID FID = SourceMgr.createFileID(File, IncludeLoc, FileCharacter,
+    FileID FID = SourceMgr.createFileID(*File, IncludeLoc, FileCharacter,
                                         ID, BaseOffset + Record[0]);
     SrcMgr::FileInfo &FileInfo =
           const_cast<SrcMgr::FileInfo&>(SourceMgr.getSLocEntry(FID).getFile());
@@ -1533,14 +1533,14 @@
     }
 
     const SrcMgr::ContentCache &ContentCache =
-        SourceMgr.getOrCreateContentCache(File, isSystem(FileCharacter));
+        SourceMgr.getOrCreateContentCache(*File, isSystem(FileCharacter));
     if (OverriddenBuffer && !ContentCache.BufferOverridden &&
         ContentCache.ContentsEntry == ContentCache.OrigEntry &&
         !ContentCache.getBufferIfLoaded()) {
       auto Buffer = ReadBuffer(SLocEntryCursor, File->getName());
       if (!Buffer)
         return true;
-      SourceMgr.overrideFileContents(File, std::move(Buffer));
+      SourceMgr.overrideFileContents(*File, std::move(Buffer));
     }
 
     break;