diff --git a/clang/include/clang/CrossTU/CrossTranslationUnit.h b/clang/include/clang/CrossTU/CrossTranslationUnit.h
--- a/clang/include/clang/CrossTU/CrossTranslationUnit.h
+++ b/clang/include/clang/CrossTU/CrossTranslationUnit.h
@@ -165,6 +165,7 @@
 private:
   bool checkThresholdReached() const;
   llvm::Error lazyInitCTUIndex(StringRef CrossTUDir, StringRef IndexName);
+  ASTUnit *getCachedASTUnitForName(StringRef LookupName) const;
   void lazyInitImporterSharedSt(TranslationUnitDecl *ToTU);
   ASTImporter &getOrCreateASTImporter(ASTContext &From);
   template <typename T>
diff --git a/clang/lib/CrossTU/CrossTranslationUnit.cpp b/clang/lib/CrossTU/CrossTranslationUnit.cpp
--- a/clang/lib/CrossTU/CrossTranslationUnit.cpp
+++ b/clang/lib/CrossTU/CrossTranslationUnit.cpp
@@ -371,6 +371,15 @@
   };
 }
 
+ASTUnit *CrossTranslationUnitContext::getCachedASTUnitForName(
+    StringRef LookupName) const {
+  auto CacheEntry = NameASTUnitMap.find(LookupName);
+  if (CacheEntry != NameASTUnitMap.end())
+    return CacheEntry->second;
+  else
+    return nullptr;
+}
+
 llvm::Expected<ASTUnit *> CrossTranslationUnitContext::loadExternalAST(
     StringRef LookupName, StringRef CrossTUDir, StringRef IndexName,
     bool DisplayCTUProgress) {
@@ -384,45 +393,45 @@
     return llvm::make_error<IndexError>(
         index_error_code::load_threshold_reached);
 
-  ASTUnit *Unit = nullptr;
-  auto NameUnitCacheEntry = NameASTUnitMap.find(LookupName);
-  if (NameUnitCacheEntry == NameASTUnitMap.end()) {
-    // Lazily initialize the mapping from function names to AST files.
-    if (llvm::Error InitFailed = lazyInitCTUIndex(CrossTUDir, IndexName))
-      return std::move(InitFailed);
-
-    auto It = NameFileMap.find(LookupName);
-    if (It == NameFileMap.end()) {
-      ++NumNotInOtherTU;
-      return llvm::make_error<IndexError>(index_error_code::missing_definition);
-    }
-    StringRef ASTFileName = It->second;
-    auto ASTCacheEntry = FileASTUnitMap.find(ASTFileName);
-    if (ASTCacheEntry == FileASTUnitMap.end()) {
-      IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
-      TextDiagnosticPrinter *DiagClient =
-          new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
-      IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
-      IntrusiveRefCntPtr<DiagnosticsEngine> Diags(
-          new DiagnosticsEngine(DiagID, &*DiagOpts, DiagClient));
-
-      std::unique_ptr<ASTUnit> LoadedUnit(ASTUnit::LoadFromASTFile(
-          ASTFileName, CI.getPCHContainerOperations()->getRawReader(),
-          ASTUnit::LoadEverything, Diags, CI.getFileSystemOpts()));
-      Unit = LoadedUnit.get();
-      FileASTUnitMap[ASTFileName] = std::move(LoadedUnit);
-      ++NumASTLoaded;
-      if (DisplayCTUProgress) {
-        llvm::errs() << "CTU loaded AST file: "
-                     << ASTFileName << "\n";
-      }
-    } else {
-      Unit = ASTCacheEntry->second.get();
+  // First try to access the cache to get the ASTUnit for the function name
+  // specified by LookupName.
+  ASTUnit *Unit = getCachedASTUnitForName(LookupName);
+  if (Unit)
+    return Unit;
+
+  // Lazily initialize the mapping from function names to AST files.
+  if (llvm::Error InitFailed = lazyInitCTUIndex(CrossTUDir, IndexName))
+    return std::move(InitFailed);
+
+  auto It = NameFileMap.find(LookupName);
+  if (It == NameFileMap.end()) {
+    ++NumNotInOtherTU;
+    return llvm::make_error<IndexError>(index_error_code::missing_definition);
+  }
+  StringRef ASTFileName = It->second;
+  auto ASTCacheEntry = FileASTUnitMap.find(ASTFileName);
+  if (ASTCacheEntry == FileASTUnitMap.end()) {
+    IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
+    TextDiagnosticPrinter *DiagClient =
+        new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
+    IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
+    IntrusiveRefCntPtr<DiagnosticsEngine> Diags(
+        new DiagnosticsEngine(DiagID, &*DiagOpts, DiagClient));
+
+    std::unique_ptr<ASTUnit> LoadedUnit(ASTUnit::LoadFromASTFile(
+        ASTFileName, CI.getPCHContainerOperations()->getRawReader(),
+        ASTUnit::LoadEverything, Diags, CI.getFileSystemOpts()));
+    Unit = LoadedUnit.get();
+    FileASTUnitMap[ASTFileName] = std::move(LoadedUnit);
+    ++NumASTLoaded;
+    if (DisplayCTUProgress) {
+      llvm::errs() << "CTU loaded AST file: " << ASTFileName << "\n";
     }
-    NameASTUnitMap[LookupName] = Unit;
   } else {
-    Unit = NameUnitCacheEntry->second;
+    Unit = ASTCacheEntry->second.get();
   }
+  NameASTUnitMap[LookupName] = Unit;
+
   if (!Unit)
     return llvm::make_error<IndexError>(
         index_error_code::failed_to_get_external_ast);