Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -303,6 +303,10 @@
     "Default architecture for OpenMP offloading to Nvidia GPUs." FORCE)
 endif()
 
+set(CLANG_SYSTEMZ_DEFAULT_ARCH "z10" CACHE STRING
+  "SystemZ Default Arch")
+add_definitions( -DCLANG_SYSTEMZ_DEFAULT_ARCH="${CLANG_SYSTEMZ_DEFAULT_ARCH}")
+
 set(CLANG_VENDOR ${PACKAGE_VENDOR} CACHE STRING
   "Vendor-specific text for showing with version information.")
 
Index: lib/Driver/ToolChains/Arch/SystemZ.cpp
===================================================================
--- lib/Driver/ToolChains/Arch/SystemZ.cpp
+++ lib/Driver/ToolChains/Arch/SystemZ.cpp
@@ -18,7 +18,7 @@
 const char *systemz::getSystemZTargetCPU(const ArgList &Args) {
   if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_march_EQ))
     return A->getValue();
-  return "z10";
+  return CLANG_SYSTEMZ_DEFAULT_ARCH;
 }
 
 void systemz::getSystemZTargetFeatures(const ArgList &Args,