diff --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
@@ -93,10 +93,9 @@
     llvm::sys::path::replace_extension(GuessedFileName,
                                        (HFE.size() ? "." : "") + HFE);
 
-    const DirectoryLookup *CurDir;
     Optional<FileEntryRef> File =
         PP->LookupFile(DiagLoc, GuessedFileName, IsAngled, nullptr, nullptr,
-                       CurDir, nullptr, nullptr, nullptr, nullptr, nullptr);
+                       nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
     if (File) {
       Check.diag(DiagLoc, "did you mean to include '%0'?", DiagnosticIDs::Note)
           << GuessedFileName;
diff --git a/clang/include/clang/Lex/HeaderSearch.h b/clang/include/clang/Lex/HeaderSearch.h
--- a/clang/include/clang/Lex/HeaderSearch.h
+++ b/clang/include/clang/Lex/HeaderSearch.h
@@ -408,7 +408,7 @@
   /// found.
   Optional<FileEntryRef> LookupFile(
       StringRef Filename, SourceLocation IncludeLoc, bool isAngled,
-      const DirectoryLookup *FromDir, const DirectoryLookup *&CurDir,
+      const DirectoryLookup *FromDir, const DirectoryLookup **CurDir,
       ArrayRef<std::pair<const FileEntry *, const DirectoryEntry *>> Includers,
       SmallVectorImpl<char> *SearchPath, SmallVectorImpl<char> *RelativePath,
       Module *RequestingModule, ModuleMap::KnownHeader *SuggestedModule,
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -2051,7 +2051,7 @@
   Optional<FileEntryRef>
   LookupFile(SourceLocation FilenameLoc, StringRef Filename, bool isAngled,
              const DirectoryLookup *FromDir, const FileEntry *FromFile,
-             const DirectoryLookup *&CurDir, SmallVectorImpl<char> *SearchPath,
+             const DirectoryLookup **CurDir, SmallVectorImpl<char> *SearchPath,
              SmallVectorImpl<char> *RelativePath,
              ModuleMap::KnownHeader *SuggestedModule, bool *IsMapped,
              bool *IsFrameworkFound, bool SkipCache = false);
@@ -2300,7 +2300,7 @@
   };
 
   Optional<FileEntryRef> LookupHeaderIncludeOrImport(
-      const DirectoryLookup *&CurDir, StringRef &Filename,
+      const DirectoryLookup **CurDir, StringRef &Filename,
       SourceLocation FilenameLoc, CharSourceRange FilenameRange,
       const Token &FilenameTok, bool &IsFrameworkFound, bool IsImportDecl,
       bool &IsMapped, const DirectoryLookup *LookupFrom,
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -310,9 +310,8 @@
   auto &HS = CI.getPreprocessor().getHeaderSearchInfo();
   SmallVector<Module::Header, 16> Headers;
   for (StringRef Name : ModuleHeaders) {
-    const DirectoryLookup *CurDir = nullptr;
     Optional<FileEntryRef> FE = HS.LookupFile(
-        Name, SourceLocation(), /*Angled*/ false, nullptr, CurDir, None,
+        Name, SourceLocation(), /*Angled*/ false, nullptr, nullptr, None,
         nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
     if (!FE) {
       CI.getDiagnostics().Report(diag::err_module_header_file_not_found)
diff --git a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
--- a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
+++ b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
@@ -541,9 +541,8 @@
           ExpectedLoc = SourceLocation();
         } else {
           // Lookup file via Preprocessor, like a #include.
-          const DirectoryLookup *CurDir;
           Optional<FileEntryRef> File =
-              PP->LookupFile(Pos, Filename, false, nullptr, nullptr, CurDir,
+              PP->LookupFile(Pos, Filename, false, nullptr, nullptr, nullptr,
                              nullptr, nullptr, nullptr, nullptr, nullptr);
           if (!File) {
             Diags.Report(Pos.getLocWithOffset(PH.C - PH.Begin),
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -831,12 +831,15 @@
 /// search is needed. Microsoft mode will pass all \#including files.
 Optional<FileEntryRef> HeaderSearch::LookupFile(
     StringRef Filename, SourceLocation IncludeLoc, bool isAngled,
-    const DirectoryLookup *FromDir, const DirectoryLookup *&CurDir,
+    const DirectoryLookup *FromDir, const DirectoryLookup **CurDirArg,
     ArrayRef<std::pair<const FileEntry *, const DirectoryEntry *>> Includers,
     SmallVectorImpl<char> *SearchPath, SmallVectorImpl<char> *RelativePath,
     Module *RequestingModule, ModuleMap::KnownHeader *SuggestedModule,
     bool *IsMapped, bool *IsFrameworkFound, bool SkipCache,
     bool BuildSystemModule) {
+  const DirectoryLookup *CurDirLocal = nullptr;
+  const DirectoryLookup *&CurDir = CurDirArg ? *CurDirArg : CurDirLocal;
+
   if (IsMapped)
     *IsMapped = false;
 
@@ -1083,7 +1086,7 @@
       ScratchFilename += Filename;
 
       Optional<FileEntryRef> File = LookupFile(
-          ScratchFilename, IncludeLoc, /*isAngled=*/true, FromDir, CurDir,
+          ScratchFilename, IncludeLoc, /*isAngled=*/true, FromDir, &CurDir,
           Includers.front(), SearchPath, RelativePath, RequestingModule,
           SuggestedModule, IsMapped, /*IsFrameworkFound=*/nullptr);
 
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -818,10 +818,13 @@
 Optional<FileEntryRef> Preprocessor::LookupFile(
     SourceLocation FilenameLoc, StringRef Filename, bool isAngled,
     const DirectoryLookup *FromDir, const FileEntry *FromFile,
-    const DirectoryLookup *&CurDir, SmallVectorImpl<char> *SearchPath,
+    const DirectoryLookup **CurDirArg, SmallVectorImpl<char> *SearchPath,
     SmallVectorImpl<char> *RelativePath,
     ModuleMap::KnownHeader *SuggestedModule, bool *IsMapped,
     bool *IsFrameworkFound, bool SkipCache) {
+  const DirectoryLookup *CurDirLocal = nullptr;
+  const DirectoryLookup *&CurDir = CurDirArg ? *CurDirArg : CurDirLocal;
+
   Module *RequestingModule = getModuleForLocation(FilenameLoc);
   bool RequestingModuleIsModuleInterface = !SourceMgr.isInMainFile(FilenameLoc);
 
@@ -877,7 +880,7 @@
     const DirectoryLookup *TmpCurDir = CurDir;
     const DirectoryLookup *TmpFromDir = nullptr;
     while (Optional<FileEntryRef> FE = HeaderInfo.LookupFile(
-               Filename, FilenameLoc, isAngled, TmpFromDir, TmpCurDir,
+               Filename, FilenameLoc, isAngled, TmpFromDir, &TmpCurDir,
                Includers, SearchPath, RelativePath, RequestingModule,
                SuggestedModule, /*IsMapped=*/nullptr,
                /*IsFrameworkFound=*/nullptr, SkipCache)) {
@@ -895,7 +898,7 @@
 
   // Do a standard file entry lookup.
   Optional<FileEntryRef> FE = HeaderInfo.LookupFile(
-      Filename, FilenameLoc, isAngled, FromDir, CurDir, Includers, SearchPath,
+      Filename, FilenameLoc, isAngled, FromDir, &CurDir, Includers, SearchPath,
       RelativePath, RequestingModule, SuggestedModule, IsMapped,
       IsFrameworkFound, SkipCache, BuildSystemModule);
   if (FE) {
@@ -1827,7 +1830,7 @@
 }
 
 Optional<FileEntryRef> Preprocessor::LookupHeaderIncludeOrImport(
-    const DirectoryLookup *&CurDir, StringRef& Filename,
+    const DirectoryLookup **CurDir, StringRef& Filename,
     SourceLocation FilenameLoc, CharSourceRange FilenameRange,
     const Token &FilenameTok, bool &IsFrameworkFound, bool IsImportDecl,
     bool &IsMapped, const DirectoryLookup *LookupFrom,
@@ -2028,7 +2031,7 @@
   }
 
   Optional<FileEntryRef> File = LookupHeaderIncludeOrImport(
-      CurDir, Filename, FilenameLoc, FilenameRange, FilenameTok,
+      &CurDir, Filename, FilenameLoc, FilenameRange, FilenameTok,
       IsFrameworkFound, IsImportDecl, IsMapped, LookupFrom, LookupFromFile,
       LookupFilename, RelativePath, SearchPath, SuggestedModule, isAngled);
 
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -1228,10 +1228,9 @@
     return false;
 
   // Search include directories.
-  const DirectoryLookup *CurDir;
   Optional<FileEntryRef> File =
       PP.LookupFile(FilenameLoc, Filename, isAngled, LookupFrom, LookupFromFile,
-                    CurDir, nullptr, nullptr, nullptr, nullptr, nullptr);
+                    nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
 
   if (PPCallbacks *Callbacks = PP.getPPCallbacks()) {
     SrcMgr::CharacteristicKind FileType = SrcMgr::C_User;
diff --git a/clang/lib/Lex/Pragma.cpp b/clang/lib/Lex/Pragma.cpp
--- a/clang/lib/Lex/Pragma.cpp
+++ b/clang/lib/Lex/Pragma.cpp
@@ -526,9 +526,8 @@
     return llvm::None;
 
   // Search include directories for this file.
-  const DirectoryLookup *CurDir;
   File = PP.LookupFile(FilenameTok.getLocation(), Filename, isAngled, nullptr,
-                       nullptr, CurDir, nullptr, nullptr, nullptr, nullptr,
+                       nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
                        nullptr);
   if (!File) {
     if (!SuppressIncludeNotFoundError)
diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -566,11 +566,10 @@
   if (!PPOpts->PCHThroughHeader.empty()) {
     // Lookup and save the FileID for the through header. If it isn't found
     // in the search path, it's a fatal error.
-    const DirectoryLookup *CurDir;
     Optional<FileEntryRef> File = LookupFile(
         SourceLocation(), PPOpts->PCHThroughHeader,
-        /*isAngled=*/false, /*FromDir=*/nullptr, /*FromFile=*/nullptr, CurDir,
-        /*SearchPath=*/nullptr, /*RelativePath=*/nullptr,
+        /*isAngled=*/false, /*FromDir=*/nullptr, /*FromFile=*/nullptr,
+        /*CurDir=*/nullptr, /*SearchPath=*/nullptr, /*RelativePath=*/nullptr,
         /*SuggestedModule=*/nullptr, /*IsMapped=*/nullptr,
         /*IsFrameworkFound=*/nullptr);
     if (!File) {
diff --git a/clang/unittests/Lex/HeaderSearchTest.cpp b/clang/unittests/Lex/HeaderSearchTest.cpp
--- a/clang/unittests/Lex/HeaderSearchTest.cpp
+++ b/clang/unittests/Lex/HeaderSearchTest.cpp
@@ -238,10 +238,9 @@
       /*User=*/None, /*Group=*/None, llvm::sys::fs::file_type::regular_file);
 
   bool IsMapped = false;
-  const DirectoryLookup *CurDir = nullptr;
   auto FoundFile = Search.LookupFile(
       "Foo/Foo.h", SourceLocation(), /*isAngled=*/true, /*FromDir=*/nullptr,
-      CurDir, /*Includers=*/{}, /*SearchPath=*/nullptr,
+      /*CurDir=*/nullptr, /*Includers=*/{}, /*SearchPath=*/nullptr,
       /*RelativePath=*/nullptr, /*RequestingModule=*/nullptr,
       /*SuggestedModule=*/nullptr, &IsMapped,
       /*IsFrameworkFound=*/nullptr);