diff --git a/lib/Transforms/IPO/ArgumentPromotion.cpp b/lib/Transforms/IPO/ArgumentPromotion.cpp
index 7036a01f090..e1fe118686e 100644
--- a/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -515,7 +515,7 @@ Function *ArgPromotion::DoPromotion(Function *F,
           std::string NewName = I->getName();
           for (unsigned i = 0, e = Operands.size(); i != e; ++i)
             if (ConstantInt *CI = dyn_cast<ConstantInt>(Operands[i]))
-              NewName += "."+itostr((int64_t)CI->getZExtValue());
+              NewName += "." + CI->getValue().toString(10);
             else
               NewName += ".x";
           TheArg->setName(NewName+".val");