Index: include/clang/Basic/VirtualFileSystem.h
===================================================================
--- include/clang/Basic/VirtualFileSystem.h
+++ include/clang/Basic/VirtualFileSystem.h
@@ -234,7 +234,7 @@
   /// closes the file.
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
   getBufferForFile(const Twine &Name, int64_t FileSize = -1,
-                   bool RequiresNullTerminator = true, bool IsVolatile = false);
+                   bool RequiresNullTerminator = true, bool IsVolatile = true);
 
   /// Get a directory_iterator for \p Dir.
   /// \note The 'end' iterator is directory_iterator().