diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 9878a9dad78d4..9b7dd189c60d7 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -458,6 +458,7 @@ DerivedArgList *Driver::TranslateInputArgs(const InputArgList &Args) const {
     // some build systems. We don't try to be complete here because we don't
     // care to encourage this usage model.
     if (A->getOption().matches(options::OPT_Wp_COMMA) &&
+        A->getNumValues() > 0 &&
         (A->getValue(0) == StringRef("-MD") ||
          A->getValue(0) == StringRef("-MMD"))) {
       // Rewrite to -MD/-MMD along with -MF.