diff --git a/include/llvm/Target/TargetMachine.h b/include/llvm/Target/TargetMachine.h
index 7dd5c4ef159..d2fe1d3c5f7 100644
--- a/include/llvm/Target/TargetMachine.h
+++ b/include/llvm/Target/TargetMachine.h
@@ -268,7 +268,7 @@ public:
   ///
   virtual bool addPassesToEmitMC(PassManagerBase &,
                                  MCContext *&,
-                                 raw_ostream &OS,
+                                 raw_ostream &,
                                  CodeGenOpt::Level,
                                  bool = true) {
     return true;