diff --git a/llvm/include/llvm/Tools/StringExtras.h b/llvm/include/llvm/Tools/StringExtras.h
index 31dedb42488d95536acf2048422699b5c37f3531..819da2f054690d761319691b1b576ad2cb876a00 100644
--- a/llvm/include/llvm/Tools/StringExtras.h
+++ b/llvm/include/llvm/Tools/StringExtras.h
@@ -9,6 +9,7 @@
 #define LLVM_TOOLS_STRING_EXTRAS_H
 
 #include <string>
+#include <stdio.h>
 #include "llvm/Tools/DataTypes.h"
 
 static inline string utostr(uint64_t X, bool isNeg = false) {
@@ -60,4 +61,10 @@ static inline string itostr(int X) {
     return utostr((unsigned)X);
 }
 
+static inline string ftostr(double V) {
+  char Buffer[200];
+  snprintf(Buffer, 200, "%f", V);
+  return Buffer;
+}
+
 #endif