diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index fc30b134e01..8c09eecd4f6 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -9837,7 +9837,8 @@ bool X86TargetLowering::ExpandInlineAsm(CallInst *CI) const {
         AsmPieces[2] == "${0:w}" &&
         IA->getConstraintString().compare(0, 5, "=r,0,") == 0) {
       AsmPieces.clear();
-      SplitString(IA->getConstraintString().substr(5), AsmPieces, ",");
+      const std::string &Constraints = IA->getConstraintString();
+      SplitString(StringRef(Constraints).substr(5), AsmPieces, ",");
       std::sort(AsmPieces.begin(), AsmPieces.end());
       if (AsmPieces.size() == 4 &&
           AsmPieces[0] == "~{cc}" &&