Index: CodeGen/MachineVerifier.cpp
===================================================================
--- CodeGen/MachineVerifier.cpp
+++ CodeGen/MachineVerifier.cpp
@@ -260,7 +260,7 @@
     static char ID; // Pass ID, replacement for typeid
     const std::string Banner;
 
-    MachineVerifierPass(const std::string &banner = nullptr)
+    MachineVerifierPass(const std::string &banner = std::string())
       : MachineFunctionPass(ID), Banner(banner) {
         initializeMachineVerifierPassPass(*PassRegistry::getPassRegistry());
       }