Index: cfe/trunk/lib/Driver/Tools.cpp
===================================================================
--- cfe/trunk/lib/Driver/Tools.cpp
+++ cfe/trunk/lib/Driver/Tools.cpp
@@ -4777,7 +4777,20 @@
 
   if (Args.hasFlag(options::OPT_fxray_instrument,
                    options::OPT_fnoxray_instrument, false)) {
-    CmdArgs.push_back("-fxray-instrument");
+    const char *const XRayInstrumentOption = "-fxray-instrument";
+    switch (getToolChain().getArch()) {
+    case llvm::Triple::arm:
+    case llvm::Triple::x86_64:
+      break;
+    default: {
+      std::string Feature(XRayInstrumentOption);
+      Feature += " on ";
+      Feature += Triple.getArchName().data();
+      D.Diag(diag::err_drv_clang_unsupported) << Feature;
+      break;
+    }
+    }
+    CmdArgs.push_back(XRayInstrumentOption);
     if (const Arg *A =
             Args.getLastArg(options::OPT_fxray_instruction_threshold_,
                             options::OPT_fxray_instruction_threshold_EQ)) {
Index: cfe/trunk/test/Driver/xray-instrument.c
===================================================================
--- cfe/trunk/test/Driver/xray-instrument.c
+++ cfe/trunk/test/Driver/xray-instrument.c
@@ -0,0 +1,3 @@
+// RUN: %clang -v -fxray-instrument -c %s
+// XFAIL: armeb, aarch64, aarch64_be, avr, bpfel, bpfeb, hexagon, mips, mipsel, mips64, mips64el, msp430, ppc, ppc64, ppc64le, r600, amdgcn, sparc, sparcv9, sparcel, systemz, tce, thumb, thumbeb, x86-, xcore, nvptx, nvptx64, le32, le64, amdil, amdil64, hsail, hsail64, spir, spir64, kalimba, shave, lanai, wasm32, wasm64, renderscript32, renderscript64
+typedef int a;