diff --git a/contrib/llvm/tools/clang/include/clang/Driver/Options.td b/contrib/llvm/tools/clang/include/clang/Driver/Options.td
index a48b7ad8282..faef3b68b8d 100644
--- a/contrib/llvm/tools/clang/include/clang/Driver/Options.td
+++ b/contrib/llvm/tools/clang/include/clang/Driver/Options.td
@@ -1141,6 +1141,9 @@ def mno_long_calls : Flag<["-"], "mno-long-calls">, Group<m_arm_Features_Group>,
 def mgeneral_regs_only : Flag<["-"], "mgeneral-regs-only">, Group<m_aarch64_Features_Group>,
   HelpText<"Generate code which only uses the general purpose registers (AArch64 only)">;
 
+def ffixed_x18 : Flag<["-"], "ffixed-x18">, Group<m_aarch64_Features_Group>,
+  HelpText<"Reserve the x18 register (AArch64 only)">;
+
 def mvsx : Flag<["-"], "mvsx">, Group<m_ppc_Features_Group>;
 def mno_vsx : Flag<["-"], "mno-vsx">, Group<m_ppc_Features_Group>;
 def mfprnd : Flag<["-"], "mfprnd">, Group<m_ppc_Features_Group>;
diff --git a/contrib/llvm/tools/clang/lib/Driver/Tools.cpp b/contrib/llvm/tools/clang/lib/Driver/Tools.cpp
index f33fb32b06a..5acffb7fd72 100644
--- a/contrib/llvm/tools/clang/lib/Driver/Tools.cpp
+++ b/contrib/llvm/tools/clang/lib/Driver/Tools.cpp
@@ -887,6 +887,11 @@ void Clang::AddAArch64TargetArgs(const ArgList &Args,
     if (A->getOption().matches(options::OPT_mno_global_merge))
       CmdArgs.push_back("-mno-global-merge");
   }
+
+  if (Args.hasArg(options::OPT_ffixed_x18)) {
+    CmdArgs.push_back("-backend-option");
+    CmdArgs.push_back("-aarch64-reserve-x18");
+  }
 }
 
 // Get CPU and ABI names. They are not independent