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
@@ -217,7 +217,7 @@
   OptionalFileEntryRef ASTFile;
 
   /// The top-level headers associated with this module.
-  llvm::SmallSetVector<const FileEntry *, 2> TopHeaders;
+  llvm::SmallSetVector<FileEntryRef, 2> TopHeaders;
 
   /// top-level header filenames that aren't resolved to FileEntries yet.
   std::vector<std::string> TopHeaderNames;
@@ -672,7 +672,7 @@
   OptionalDirectoryEntryRef getEffectiveUmbrellaDir() const;
 
   /// Add a top-level header associated with this module.
-  void addTopHeader(const FileEntry *File);
+  void addTopHeader(FileEntryRef File);
 
   /// Add a top-level header filename associated with this module.
   void addTopHeaderFilename(StringRef Filename) {
@@ -680,7 +680,7 @@
   }
 
   /// The top-level headers associated with this module.
-  ArrayRef<const FileEntry *> getTopHeaders(FileManager &FileMgr);
+  ArrayRef<FileEntryRef> getTopHeaders(FileManager &FileMgr);
 
   /// Determine whether this module has declared its intention to
   /// directly use another module.
diff --git a/clang/include/clang/Frontend/ASTUnit.h b/clang/include/clang/Frontend/ASTUnit.h
--- a/clang/include/clang/Frontend/ASTUnit.h
+++ b/clang/include/clang/Frontend/ASTUnit.h
@@ -643,7 +643,7 @@
   bool visitLocalTopLevelDecls(void *context, DeclVisitorFn Fn);
 
   /// Get the PCH file if one was included.
-  const FileEntry *getPCHFile();
+  OptionalFileEntryRef getPCHFile();
 
   /// Returns true if the ASTUnit was constructed from a serialized
   /// module file.
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
@@ -271,18 +271,16 @@
   return std::nullopt;
 }
 
-void Module::addTopHeader(const FileEntry *File) {
+void Module::addTopHeader(FileEntryRef File) {
   assert(File);
   TopHeaders.insert(File);
 }
 
-ArrayRef<const FileEntry *> Module::getTopHeaders(FileManager &FileMgr) {
+ArrayRef<FileEntryRef> Module::getTopHeaders(FileManager &FileMgr) {
   if (!TopHeaderNames.empty()) {
-    for (std::vector<std::string>::iterator
-           I = TopHeaderNames.begin(), E = TopHeaderNames.end(); I != E; ++I) {
-      if (auto FE = FileMgr.getFile(*I))
+    for (StringRef TopHeaderName : TopHeaderNames)
+      if (auto FE = FileMgr.getOptionalFileRef(TopHeaderName))
         TopHeaders.insert(*FE);
-    }
     TopHeaderNames.clear();
   }
 
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -2645,9 +2645,9 @@
   return true;
 }
 
-const FileEntry *ASTUnit::getPCHFile() {
+OptionalFileEntryRef ASTUnit::getPCHFile() {
   if (!Reader)
-    return nullptr;
+    return std::nullopt;
 
   serialization::ModuleFile *Mod = nullptr;
   Reader->getModuleManager().visit([&Mod](serialization::ModuleFile &M) {
@@ -2670,7 +2670,7 @@
   if (Mod)
     return Mod->File;
 
-  return nullptr;
+  return std::nullopt;
 }
 
 bool ASTUnit::isModuleFile() const {
diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -379,9 +379,7 @@
     llvm::sys::path::native(UmbrellaDir->Entry.getName(), DirNative);
 
     llvm::vfs::FileSystem &FS = FileMgr.getVirtualFileSystem();
-    SmallVector<
-        std::pair<std::string, OptionalFileEntryRefDegradesToFileEntryPtr>, 8>
-        Headers;
+    SmallVector<std::pair<std::string, FileEntryRef>, 8> Headers;
     for (llvm::vfs::recursive_directory_iterator Dir(FS, DirNative, EC), End;
          Dir != End && !EC; Dir.increment(EC)) {
       // Check whether this entry has an extension typically associated with
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -2879,10 +2879,9 @@
 
     // Emit the top headers.
     {
-      auto TopHeaders = Mod->getTopHeaders(PP->getFileManager());
       RecordData::value_type Record[] = {SUBMODULE_TOPHEADER};
-      for (auto *H : TopHeaders) {
-        SmallString<128> HeaderName(H->getName());
+      for (FileEntryRef H : Mod->getTopHeaders(PP->getFileManager())) {
+        SmallString<128> HeaderName(H.getName());
         PreparePathForOutput(HeaderName);
         Stream.EmitRecordWithBlob(TopHeaderAbbrev, Record, HeaderName);
       }
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
@@ -15,6 +15,7 @@
 #include "CIndexer.h"
 #include "CLog.h"
 #include "CXCursor.h"
+#include "CXFile.h"
 #include "CXSourceLocation.h"
 #include "CXString.h"
 #include "CXTranslationUnit.h"
@@ -4662,16 +4663,16 @@
   if (!SFile)
     return cxstring::createNull();
 
-  FileEntry *FEnt = static_cast<FileEntry *>(SFile);
-  return cxstring::createRef(FEnt->getName());
+  FileEntryRef FEnt = *cxfile::getFileEntryRef(SFile);
+  return cxstring::createRef(FEnt.getName());
 }
 
 time_t clang_getFileTime(CXFile SFile) {
   if (!SFile)
     return 0;
 
-  FileEntry *FEnt = static_cast<FileEntry *>(SFile);
-  return FEnt->getModificationTime();
+  FileEntryRef FEnt = *cxfile::getFileEntryRef(SFile);
+  return FEnt.getModificationTime();
 }
 
 CXFile clang_getFile(CXTranslationUnit TU, const char *file_name) {
@@ -4683,10 +4684,7 @@
   ASTUnit *CXXUnit = cxtu::getASTUnit(TU);
 
   FileManager &FMgr = CXXUnit->getFileManager();
-  auto File = FMgr.getFile(file_name);
-  if (!File)
-    return nullptr;
-  return const_cast<FileEntry *>(*File);
+  return cxfile::makeCXFile(FMgr.getOptionalFileRef(file_name));
 }
 
 const char *clang_getFileContents(CXTranslationUnit TU, CXFile file,
@@ -4697,7 +4695,7 @@
   }
 
   const SourceManager &SM = cxtu::getASTUnit(TU)->getSourceManager();
-  FileID fid = SM.translateFile(static_cast<FileEntry *>(file));
+  FileID fid = SM.translateFile(*cxfile::getFileEntryRef(file));
   std::optional<llvm::MemoryBufferRef> buf = SM.getBufferOrNone(fid);
   if (!buf) {
     if (size)
@@ -4719,7 +4717,7 @@
     return 0;
 
   ASTUnit *CXXUnit = cxtu::getASTUnit(TU);
-  FileEntry *FEnt = static_cast<FileEntry *>(file);
+  FileEntryRef FEnt = *cxfile::getFileEntryRef(file);
   return CXXUnit->getPreprocessor()
       .getHeaderSearchInfo()
       .isFileMultipleIncludeGuarded(FEnt);
@@ -4729,11 +4727,11 @@
   if (!file || !outID)
     return 1;
 
-  FileEntry *FEnt = static_cast<FileEntry *>(file);
-  const llvm::sys::fs::UniqueID &ID = FEnt->getUniqueID();
+  FileEntryRef FEnt = *cxfile::getFileEntryRef(file);
+  const llvm::sys::fs::UniqueID &ID = FEnt.getUniqueID();
   outID->data[0] = ID.getDevice();
   outID->data[1] = ID.getFile();
-  outID->data[2] = FEnt->getModificationTime();
+  outID->data[2] = FEnt.getModificationTime();
   return 0;
 }
 
@@ -4744,17 +4742,17 @@
   if (!file1 || !file2)
     return false;
 
-  FileEntry *FEnt1 = static_cast<FileEntry *>(file1);
-  FileEntry *FEnt2 = static_cast<FileEntry *>(file2);
-  return FEnt1->getUniqueID() == FEnt2->getUniqueID();
+  FileEntryRef FEnt1 = *cxfile::getFileEntryRef(file1);
+  FileEntryRef FEnt2 = *cxfile::getFileEntryRef(file2);
+  return FEnt1.getUniqueID() == FEnt2.getUniqueID();
 }
 
 CXString clang_File_tryGetRealPathName(CXFile SFile) {
   if (!SFile)
     return cxstring::createNull();
 
-  FileEntry *FEnt = static_cast<FileEntry *>(SFile);
-  return cxstring::createRef(FEnt->tryGetRealPathName());
+  FileEntryRef FEnt = *cxfile::getFileEntryRef(SFile);
+  return cxstring::createRef(FEnt.getFileEntry().tryGetRealPathName());
 }
 
 //===----------------------------------------------------------------------===//
@@ -8601,8 +8599,7 @@
     return nullptr;
 
   const InclusionDirective *ID = getCursorInclusionDirective(cursor);
-  OptionalFileEntryRef File = ID->getFile();
-  return const_cast<FileEntry *>(File ? &File->getFileEntry() : nullptr);
+  return cxfile::makeCXFile(ID->getFile());
 }
 
 unsigned clang_Cursor_getObjCPropertyAttributes(CXCursor C, unsigned reserved) {
@@ -8798,12 +8795,11 @@
   }
   if (!File)
     return nullptr;
-  FileEntry *FE = static_cast<FileEntry *>(File);
+  FileEntryRef FE = *cxfile::getFileEntryRef(File);
 
   ASTUnit &Unit = *cxtu::getASTUnit(TU);
   HeaderSearch &HS = Unit.getPreprocessor().getHeaderSearchInfo();
-  // TODO: Make CXFile a FileEntryRef.
-  ModuleMap::KnownHeader Header = HS.findModuleForHeader(FE->getLastRef());
+  ModuleMap::KnownHeader Header = HS.findModuleForHeader(FE);
 
   return Header.getModule();
 }
@@ -8812,9 +8808,7 @@
   if (!CXMod)
     return nullptr;
   Module *Mod = static_cast<Module *>(CXMod);
-  if (auto File = Mod->getASTFile())
-    return const_cast<FileEntry *>(&File->getFileEntry());
-  return nullptr;
+  return cxfile::makeCXFile(Mod->getASTFile());
 }
 
 CXModule clang_Module_getParent(CXModule CXMod) {
@@ -8855,7 +8849,7 @@
     return 0;
   Module *Mod = static_cast<Module *>(CXMod);
   FileManager &FileMgr = cxtu::getASTUnit(TU)->getFileManager();
-  ArrayRef<const FileEntry *> TopHeaders = Mod->getTopHeaders(FileMgr);
+  ArrayRef<FileEntryRef> TopHeaders = Mod->getTopHeaders(FileMgr);
   return TopHeaders.size();
 }
 
@@ -8870,9 +8864,9 @@
   Module *Mod = static_cast<Module *>(CXMod);
   FileManager &FileMgr = cxtu::getASTUnit(TU)->getFileManager();
 
-  ArrayRef<const FileEntry *> TopHeaders = Mod->getTopHeaders(FileMgr);
+  ArrayRef<FileEntryRef> TopHeaders = Mod->getTopHeaders(FileMgr);
   if (Index < TopHeaders.size())
-    return const_cast<FileEntry *>(TopHeaders[Index]);
+    return cxfile::makeCXFile(TopHeaders[Index]);
 
   return nullptr;
 }
@@ -9248,7 +9242,7 @@
 
   ASTContext &Ctx = astUnit->getASTContext();
   SourceManager &sm = Ctx.getSourceManager();
-  FileEntry *fileEntry = static_cast<FileEntry *>(file);
+  FileEntryRef fileEntry = *cxfile::getFileEntryRef(file);
   FileID wantedFileID = sm.translateFile(fileEntry);
   bool isMainFile = wantedFileID == sm.getMainFileID();
 
@@ -9522,8 +9516,8 @@
   return *this;
 }
 
-Logger &cxindex::Logger::operator<<(const FileEntry *FE) {
-  *this << FE->getName();
+Logger &cxindex::Logger::operator<<(FileEntryRef FE) {
+  *this << FE.getName();
   return *this;
 }
 
diff --git a/clang/tools/libclang/CIndexHigh.cpp b/clang/tools/libclang/CIndexHigh.cpp
--- a/clang/tools/libclang/CIndexHigh.cpp
+++ b/clang/tools/libclang/CIndexHigh.cpp
@@ -9,6 +9,7 @@
 #include "CursorVisitor.h"
 #include "CLog.h"
 #include "CXCursor.h"
+#include "CXFile.h"
 #include "CXSourceLocation.h"
 #include "CXTranslationUnit.h"
 #include "clang/AST/DeclObjC.h"
@@ -432,7 +433,7 @@
   }
 
   if (Log)
-    *Log << cursor << " @" << static_cast<const FileEntry *>(file);
+    *Log << cursor << " @" << *cxfile::getFileEntryRef(file);
 
   ASTUnit *CXXUnit = cxcursor::getCursorASTUnit(cursor);
   if (!CXXUnit)
@@ -444,7 +445,7 @@
       cursor.kind == CXCursor_MacroExpansion) {
     if (findMacroRefsInFile(cxcursor::getCursorTU(cursor),
                             cursor,
-                            static_cast<const FileEntry *>(file),
+                            *cxfile::getFileEntryRef(file),
                             visitor))
       return CXResult_VisitBreak;
     return CXResult_Success;
@@ -469,7 +470,7 @@
 
   if (findIdRefsInFile(cxcursor::getCursorTU(cursor),
                        refCursor,
-                       static_cast<const FileEntry *>(file),
+                       *cxfile::getFileEntryRef(file),
                        visitor))
     return CXResult_VisitBreak;
   return CXResult_Success;
@@ -495,7 +496,7 @@
   }
 
   if (Log)
-    *Log << TU << " @" << static_cast<const FileEntry *>(file);
+    *Log << TU << " @" << *cxfile::getFileEntryRef(file);
 
   ASTUnit *CXXUnit = cxtu::getASTUnit(TU);
   if (!CXXUnit)
@@ -503,7 +504,7 @@
 
   ASTUnit::ConcurrencyCheck Check(*CXXUnit);
 
-  if (findIncludesInFile(TU, static_cast<const FileEntry *>(file), visitor))
+  if (findIncludesInFile(TU, *cxfile::getFileEntryRef(file), visitor))
     return CXResult_VisitBreak;
   return CXResult_Success;
 }
diff --git a/clang/tools/libclang/CIndexInclusionStack.cpp b/clang/tools/libclang/CIndexInclusionStack.cpp
--- a/clang/tools/libclang/CIndexInclusionStack.cpp
+++ b/clang/tools/libclang/CIndexInclusionStack.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "CIndexer.h"
+#include "CXFile.h"
 #include "CXSourceLocation.h"
 #include "CXTranslationUnit.h"
 #include "clang/AST/DeclVisitor.h"
@@ -58,9 +59,7 @@
       InclusionStack.pop_back();
 
     // Callback to the client.
-    // FIXME: We should have a function to construct CXFiles.
-    CB(static_cast<CXFile>(const_cast<FileEntry *>(
-           static_cast<const FileEntry *>(FI.getContentCache().OrigEntry))),
+    CB(cxfile::makeCXFile(*FI.getContentCache().OrigEntry),
        InclusionStack.data(), InclusionStack.size(), clientData);
   }
 }
diff --git a/clang/tools/libclang/CLog.h b/clang/tools/libclang/CLog.h
--- a/clang/tools/libclang/CLog.h
+++ b/clang/tools/libclang/CLog.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLS_LIBCLANG_CLOG_H
 
 #include "clang-c/Index.h"
+#include "clang/Basic/FileEntry.h"
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/SmallString.h"
@@ -23,8 +24,6 @@
 }
 
 namespace clang {
-  class FileEntry;
-
 namespace cxindex {
 
 class Logger;
@@ -65,7 +64,7 @@
   ~Logger();
 
   Logger &operator<<(CXTranslationUnit);
-  Logger &operator<<(const FileEntry *FE);
+  Logger &operator<<(FileEntryRef FE);
   Logger &operator<<(CXCursor cursor);
   Logger &operator<<(CXSourceLocation);
   Logger &operator<<(CXSourceRange);
diff --git a/clang/tools/libclang/CXFile.h b/clang/tools/libclang/CXFile.h
new file mode 100644
--- /dev/null
+++ b/clang/tools/libclang/CXFile.h
@@ -0,0 +1,29 @@
+//===- CXFile.h - Routines for manipulating CXFile --------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_LIBCLANG_CXFILE_H
+#define LLVM_CLANG_TOOLS_LIBCLANG_CXFILE_H
+
+#include "clang-c/CXFile.h"
+#include "clang/Basic/FileEntry.h"
+
+namespace clang {
+namespace cxfile {
+inline CXFile makeCXFile(OptionalFileEntryRef FE) {
+  return CXFile(FE ? &FE->getMapEntry() : nullptr);
+}
+
+inline OptionalFileEntryRef getFileEntryRef(CXFile File) {
+  if (!File)
+    return std::nullopt;
+  return FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(File));
+}
+} // namespace cxfile
+} // namespace clang
+
+#endif
diff --git a/clang/tools/libclang/CXIndexDataConsumer.h b/clang/tools/libclang/CXIndexDataConsumer.h
--- a/clang/tools/libclang/CXIndexDataConsumer.h
+++ b/clang/tools/libclang/CXIndexDataConsumer.h
@@ -360,14 +360,14 @@
 
   bool hasDiagnosticCallback() const { return CB.diagnostic; }
 
-  void enteredMainFile(const FileEntry *File);
+  void enteredMainFile(OptionalFileEntryRef File);
 
   void ppIncludedFile(SourceLocation hashLoc, StringRef filename,
                       OptionalFileEntryRef File, bool isImport, bool isAngled,
                       bool isModuleImport);
 
   void importedModule(const ImportDecl *ImportD);
-  void importedPCH(const FileEntry *File);
+  void importedPCH(FileEntryRef File);
 
   void startedTranslationUnit();
 
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
@@ -8,6 +8,7 @@
 
 #include "CXIndexDataConsumer.h"
 #include "CIndexDiagnostic.h"
+#include "CXFile.h"
 #include "CXTranslationUnit.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/DeclCXX.h"
@@ -451,13 +452,11 @@
   return CB.abortQuery(ClientData, nullptr);
 }
 
-void CXIndexDataConsumer::enteredMainFile(const FileEntry *File) {
+void CXIndexDataConsumer::enteredMainFile(OptionalFileEntryRef File) {
   if (File && CB.enteredMainFile) {
     CXIdxClientFile idxFile =
-      CB.enteredMainFile(ClientData,
-                         static_cast<CXFile>(const_cast<FileEntry *>(File)),
-                         nullptr);
-    FileMap[File] = idxFile;
+        CB.enteredMainFile(ClientData, cxfile::makeCXFile(*File), nullptr);
+    FileMap[*File] = idxFile;
   }
 }
 
@@ -474,8 +473,7 @@
   ScratchAlloc SA(*this);
   CXIdxIncludedFileInfo Info = { getIndexLoc(hashLoc),
                                  SA.toCStr(filename),
-                                 static_cast<CXFile>(
-                                   const_cast<FileEntry *>(FE)),
+                                 cxfile::makeCXFile(File),
                                  isImport, isAngled, isModuleImport };
   CXIdxClientFile idxFile = CB.ppIncludedFile(ClientData, &Info);
   FileMap[FE] = idxFile;
@@ -497,23 +495,20 @@
     if (SrcMod->getTopLevelModule() == Mod->getTopLevelModule())
       return;
 
-  FileEntry *FE = nullptr;
-  if (auto File = Mod->getASTFile())
-    FE = const_cast<FileEntry *>(&File->getFileEntry());
-  CXIdxImportedASTFileInfo Info = {static_cast<CXFile>(FE), Mod,
+  OptionalFileEntryRef FE = Mod->getASTFile();
+  CXIdxImportedASTFileInfo Info = {cxfile::makeCXFile(FE), Mod,
                                    getIndexLoc(ImportD->getLocation()),
                                    ImportD->isImplicit()};
   CXIdxClientASTFile astFile = CB.importedASTFile(ClientData, &Info);
   (void)astFile;
 }
 
-void CXIndexDataConsumer::importedPCH(const FileEntry *File) {
+void CXIndexDataConsumer::importedPCH(FileEntryRef File) {
   if (!CB.importedASTFile)
     return;
 
   CXIdxImportedASTFileInfo Info = {
-                                    static_cast<CXFile>(
-                                      const_cast<FileEntry *>(File)),
+                                    cxfile::makeCXFile(File),
                                     /*module=*/nullptr,
                                     getIndexLoc(SourceLocation()),
                                     /*isImplicit=*/false
@@ -1108,11 +1103,11 @@
   if (FID.isInvalid())
     return;
   
-  const FileEntry *FE = SM.getFileEntryForID(FID);
+  OptionalFileEntryRefDegradesToFileEntryPtr FE = SM.getFileEntryRefForID(FID);
   if (indexFile)
     *indexFile = getIndexFile(FE);
   if (file)
-    *file = const_cast<FileEntry *>(FE);
+    *file = cxfile::makeCXFile(FE);
   if (line)
     *line = SM.getLineNumber(FID, FileOffset);
   if (column)
diff --git a/clang/tools/libclang/CXLoadedDiagnostic.cpp b/clang/tools/libclang/CXLoadedDiagnostic.cpp
--- a/clang/tools/libclang/CXLoadedDiagnostic.cpp
+++ b/clang/tools/libclang/CXLoadedDiagnostic.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "CXLoadedDiagnostic.h"
+#include "CXFile.h"
 #include "CXString.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/FileManager.h"
@@ -44,7 +45,7 @@
   
   FileSystemOptions FO;
   FileManager FakeFiles;
-  llvm::DenseMap<unsigned, const FileEntry *> Files;
+  llvm::DenseMap<unsigned, FileEntryRef> Files;
 
   /// Copy the string into our own allocator.
   const char *copyString(StringRef Blob) {
@@ -275,9 +276,10 @@
   if (FileID == 0)
     LoadedLoc.file = nullptr;
   else {
-    LoadedLoc.file = const_cast<FileEntry *>(TopDiags->Files[FileID]);
-    if (!LoadedLoc.file)
+    auto It = TopDiags->Files.find(FileID);
+    if (It == TopDiags->Files.end())
       return reportInvalidFile("Corrupted file entry in source location");
+    LoadedLoc.file = cxfile::makeCXFile(It->second);
   }
   LoadedLoc.line = SDLoc.Line;
   LoadedLoc.column = SDLoc.Col;
@@ -342,8 +344,8 @@
   if (Name.size() > 65536)
     return reportInvalidFile("Out-of-bounds string in filename");
   TopDiags->FileNames[ID] = TopDiags->copyString(Name);
-  TopDiags->Files[ID] =
-      TopDiags->FakeFiles.getVirtualFile(Name, Size, Timestamp);
+  TopDiags->Files.insert(
+      {ID, TopDiags->FakeFiles.getVirtualFileRef(Name, Size, Timestamp)});
   return std::error_code();
 }
 
diff --git a/clang/tools/libclang/CXSourceLocation.cpp b/clang/tools/libclang/CXSourceLocation.cpp
--- a/clang/tools/libclang/CXSourceLocation.cpp
+++ b/clang/tools/libclang/CXSourceLocation.cpp
@@ -13,6 +13,7 @@
 #include "CXSourceLocation.h"
 #include "CIndexer.h"
 #include "CLog.h"
+#include "CXFile.h"
 #include "CXLoadedDiagnostic.h"
 #include "CXString.h"
 #include "CXTranslationUnit.h"
@@ -128,19 +129,19 @@
   LogRef Log = Logger::make(__func__);
   ASTUnit *CXXUnit = cxtu::getASTUnit(TU);
   ASTUnit::ConcurrencyCheck Check(*CXXUnit);
-  const FileEntry *File = static_cast<const FileEntry *>(file);
+  FileEntryRef File = *cxfile::getFileEntryRef(file);
   SourceLocation SLoc = CXXUnit->getLocation(File, line, column);
   if (SLoc.isInvalid()) {
     if (Log)
       *Log << llvm::format("(\"%s\", %d, %d) = invalid",
-                           File->getName().str().c_str(), line, column);
+                           File.getName().str().c_str(), line, column);
     return clang_getNullLocation();
   }
   
   CXSourceLocation CXLoc =
       cxloc::translateSourceLocation(CXXUnit->getASTContext(), SLoc);
   if (Log)
-    *Log << llvm::format("(\"%s\", %d, %d) = ", File->getName().str().c_str(),
+    *Log << llvm::format("(\"%s\", %d, %d) = ", File.getName().str().c_str(),
                          line, column)
          << CXLoc;
 
@@ -160,7 +161,7 @@
   ASTUnit *CXXUnit = cxtu::getASTUnit(TU);
 
   SourceLocation SLoc 
-    = CXXUnit->getLocation(static_cast<const FileEntry *>(file), offset);
+    = CXXUnit->getLocation(*cxfile::getFileEntryRef(file), offset);
 
   if (SLoc.isInvalid())
     return clang_getNullLocation();
@@ -251,7 +252,7 @@
   }
   
   if (file)
-    *file = const_cast<FileEntry *>(SM.getFileEntryForSLocEntry(sloc));
+    *file = cxfile::makeCXFile(SM.getFileEntryRefForID(fileID));
   if (line)
     *line = SM.getExpansionLineNumber(ExpansionLoc);
   if (column)
@@ -328,7 +329,7 @@
     return createNullLocation(file, line, column, offset);
   
   if (file)
-    *file = const_cast<FileEntry *>(SM.getFileEntryForID(FID));
+    *file = cxfile::makeCXFile(SM.getFileEntryRefForID(FID));
   if (line)
     *line = SM.getLineNumber(FID, FileOffset);
   if (column)
@@ -364,7 +365,7 @@
     return createNullLocation(file, line, column, offset);
 
   if (file)
-    *file = const_cast<FileEntry *>(SM.getFileEntryForID(FID));
+    *file = cxfile::makeCXFile(SM.getFileEntryRefForID(FID));
   if (line)
     *line = SM.getLineNumber(FID, FileOffset);
   if (column)
diff --git a/clang/tools/libclang/Indexing.cpp b/clang/tools/libclang/Indexing.cpp
--- a/clang/tools/libclang/Indexing.cpp
+++ b/clang/tools/libclang/Indexing.cpp
@@ -255,7 +255,8 @@
 
     if (Loc == MainFileLoc && Reason == PPCallbacks::EnterFile) {
       IsMainFileEntered = true;
-      DataConsumer.enteredMainFile(SM.getFileEntryForID(SM.getMainFileID()));
+      DataConsumer.enteredMainFile(
+          *SM.getFileEntryRefForID(SM.getMainFileID()));
     }
   }
 
@@ -350,8 +351,8 @@
     PreprocessorOptions &PPOpts = CI.getPreprocessorOpts();
 
     if (!PPOpts.ImplicitPCHInclude.empty()) {
-      auto File = CI.getFileManager().getFile(PPOpts.ImplicitPCHInclude);
-      if (File)
+      if (auto File =
+              CI.getFileManager().getOptionalFileRef(PPOpts.ImplicitPCHInclude))
         DataConsumer->importedPCH(*File);
     }
 
@@ -694,17 +695,18 @@
 
   ASTUnit::ConcurrencyCheck Check(*Unit);
 
-  if (const FileEntry *PCHFile = Unit->getPCHFile())
-    DataConsumer.importedPCH(PCHFile);
+  if (OptionalFileEntryRef PCHFile = Unit->getPCHFile())
+    DataConsumer.importedPCH(*PCHFile);
 
   FileManager &FileMgr = Unit->getFileManager();
 
   if (Unit->getOriginalSourceFileName().empty())
-    DataConsumer.enteredMainFile(nullptr);
-  else if (auto MainFile = FileMgr.getFile(Unit->getOriginalSourceFileName()))
+    DataConsumer.enteredMainFile(std::nullopt);
+  else if (auto MainFile =
+               FileMgr.getFileRef(Unit->getOriginalSourceFileName()))
     DataConsumer.enteredMainFile(*MainFile);
   else
-    DataConsumer.enteredMainFile(nullptr);
+    DataConsumer.enteredMainFile(std::nullopt);
 
   DataConsumer.setASTContext(Unit->getASTContext());
   DataConsumer.startedTranslationUnit();