Index: lib/Serialization/ASTReader.cpp
===================================================================
--- lib/Serialization/ASTReader.cpp
+++ lib/Serialization/ASTReader.cpp
@@ -3650,9 +3650,13 @@
   std::string TimestampFilename = MF.getTimestampFilename();
   std::error_code EC;
   llvm::raw_fd_ostream OS(TimestampFilename, EC, llvm::sys::fs::F_Text);
-  if (EC)
+  if (EC) {
+    OS.clear_error(); // Avoid triggering a fatal error.
     return;
+  }
   OS << "Timestamp file\n";
+  OS.close();
+  OS.clear_error(); // Avoid triggering a fatal error.
 }
 
 /// \brief Given a cursor at the start of an AST file, scan ahead and drop the