Index: include/clang/Driver/CC1Options.td
===================================================================
--- include/clang/Driver/CC1Options.td
+++ include/clang/Driver/CC1Options.td
@@ -218,6 +218,8 @@
   HelpText<"Limit the number of registers available for integer arguments">;
 def mrelocation_model : Separate<["-"], "mrelocation-model">,
   HelpText<"The relocation model to use">;
+def mthread_model : Separate<["-"], "mthread-model">,
+  HelpText<"The thread model to use">;
 def munwind_tables : Flag<["-"], "munwind-tables">,
   HelpText<"Generate unwinding tables for all functions">;
 def mconstructor_aliases : Flag<["-"], "mconstructor-aliases">,
Index: include/clang/Driver/ToolChain.h
===================================================================
--- include/clang/Driver/ToolChain.h
+++ include/clang/Driver/ToolChain.h
@@ -248,6 +248,9 @@
   /// UseSjLjExceptions - Does this tool chain use SjLj exceptions.
   virtual bool UseSjLjExceptions() const { return false; }
 
+  /// getThreadModel() - Which thread model does this target use?
+  virtual std::string getThreadModel() const { return "POSIX"; }
+
   /// ComputeLLVMTriple - Return the LLVM target triple to use, after taking
   /// command line arguments into account.
   virtual std::string
Index: include/clang/Frontend/CodeGenOptions.h
===================================================================
--- include/clang/Frontend/CodeGenOptions.h
+++ include/clang/Frontend/CodeGenOptions.h
@@ -134,6 +134,9 @@
   /// The name of the relocation model to use.
   std::string RelocationModel;
 
+  /// The thread model to use
+  std::string ThreadModel;
+
   /// Path to blacklist file for sanitizers.
   std::string SanitizerBlacklistFile;
 
Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -419,6 +419,16 @@
 
   llvm::TargetOptions Options;
 
+  Options.ThreadModel = llvm::ThreadModel::POSIX;
+  if (CodeGenOpts.ThreadModel == "POSIX") {
+    Options.ThreadModel = llvm::ThreadModel::POSIX;
+  } else if (CodeGenOpts.ThreadModel == "Single") {
+    Options.ThreadModel = llvm::ThreadModel::Single;
+  } else {
+    assert(false && "Invalid Thread model!");
+    Options.ThreadModel = llvm::ThreadModel::POSIX;
+  }
+
   if (CodeGenOpts.DisableIntegratedAS)
     Options.DisableIntegratedAS = true;
 
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -2776,6 +2776,9 @@
     }
   }
 
+  CmdArgs.push_back("-mthread-model");
+  CmdArgs.push_back(Args.MakeArgString(getToolChain().getThreadModel()));
+
   if (!Args.hasFlag(options::OPT_fmerge_all_constants,
                     options::OPT_fno_merge_all_constants))
     CmdArgs.push_back("-fno-merge-all-constants");
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -437,6 +437,7 @@
                       Args.hasArg(OPT_cl_fast_relaxed_math);
   Opts.UnwindTables = Args.hasArg(OPT_munwind_tables);
   Opts.RelocationModel = Args.getLastArgValue(OPT_mrelocation_model, "pic");
+  Opts.ThreadModel = Args.getLastArgValue(OPT_mthread_model, "POSIX");
   Opts.TrapFuncName = Args.getLastArgValue(OPT_ftrap_function_EQ);
   Opts.UseInitArray = Args.hasArg(OPT_fuse_init_array);