Index: lib/Support/CommandLine.cpp
===================================================================
--- lib/Support/CommandLine.cpp
+++ lib/Support/CommandLine.cpp
@@ -975,6 +975,8 @@
       // move on.
       AllExpanded = false;
       ++I;
+      // Emit warning if response file is not found, it might be misprint.
+      errs() << "Response file '" << Arg + 1 << "' not found\n";
       continue;
     }
     Argv.erase(Argv.begin() + I);