diff -u -r ../llvm-4.0.0.src/tools/llvm-xray/xray-converter.cc ./tools/llvm-xray/xray-converter.cc
--- ../llvm-4.0.0.src/tools/llvm-xray/xray-converter.cc	2017-02-27 18:01:04.000000000 +0100
+++ ./tools/llvm-xray/xray-converter.cc	2017-03-14 18:30:35.979011376 +0100
@@ -14,6 +14,7 @@
 
 #include "xray-extract.h"
 #include "xray-registry.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/DebugInfo/Symbolize/Symbolize.h"
 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/FileSystem.h"
@@ -95,7 +96,7 @@
   for (const auto &R : Records) {
     Trace.Records.push_back({R.RecordType, R.CPU, R.Type, R.FuncId,
                              Symbolize ? FuncIdHelper.SymbolOrNumber(R.FuncId)
-                                       : std::to_string(R.FuncId),
+                                       : llvm::utostr(R.FuncId),
                              R.TSC, R.TId});
   }
   Output Out(OS, nullptr, 0);