Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -4767,6 +4767,17 @@
 
   if (Args.hasFlag(options::OPT_fxray_instrument,
                    options::OPT_fnoxray_instrument, false)) {
+    switch(getToolChain().getArch()) {
+    case llvm::Triple::arm:
+    case llvm::Triple::x86_64:
+      break;
+    default:
+    {
+      std::string feature("XRay for ");
+      feature += Triple.getArchName().data();
+      D.Diag(diag::err_drv_clang_unsupported) << feature;
+      break;
+    } }
     CmdArgs.push_back("-fxray-instrument");
     if (const Arg *A =
             Args.getLastArg(options::OPT_fxray_instruction_threshold_,