diff --git a/clang/include/clang/Serialization/GlobalModuleIndex.h b/clang/include/clang/Serialization/GlobalModuleIndex.h
--- a/clang/include/clang/Serialization/GlobalModuleIndex.h
+++ b/clang/include/clang/Serialization/GlobalModuleIndex.h
@@ -113,7 +113,7 @@
 
   /// Internal constructor. Use \c readIndex() to read an index.
   explicit GlobalModuleIndex(std::unique_ptr<llvm::MemoryBuffer> Buffer,
-                             llvm::BitstreamCursor Cursor);
+                             llvm::BitstreamCursor &Cursor);
 
   GlobalModuleIndex(const GlobalModuleIndex &) = delete;
   GlobalModuleIndex &operator=(const GlobalModuleIndex &) = delete;
diff --git a/clang/lib/Serialization/GlobalModuleIndex.cpp b/clang/lib/Serialization/GlobalModuleIndex.cpp
--- a/clang/lib/Serialization/GlobalModuleIndex.cpp
+++ b/clang/lib/Serialization/GlobalModuleIndex.cpp
@@ -127,7 +127,7 @@
 
 GlobalModuleIndex::GlobalModuleIndex(
     std::unique_ptr<llvm::MemoryBuffer> IndexBuffer,
-    llvm::BitstreamCursor Cursor)
+    llvm::BitstreamCursor &Cursor)
     : Buffer(std::move(IndexBuffer)), IdentifierIndex(), NumIdentifierLookups(),
       NumIdentifierLookupHits() {
   auto Fail = [&](llvm::Error &&Err) {