Describe the value name

llvm-svn: 7493
diff --git a/llvm/lib/Support/Timer.cpp b/llvm/lib/Support/Timer.cpp
index 3672feb..9800128 100644
--- a/llvm/lib/Support/Timer.cpp
+++ b/llvm/lib/Support/Timer.cpp
@@ -39,7 +39,7 @@
 #endif
 
   cl::opt<std::string, true>
-  InfoOutputFilename("info-output-file",
+  InfoOutputFilename("info-output-file", cl::value_desc("filename"),
                      cl::desc("File to append -stats and -timer output to"),
                    cl::Hidden, cl::location(getLibSupportInfoOutputFilename()));
 }