Index: cfe/trunk/lib/Basic/Targets.cpp
===================================================================
--- cfe/trunk/lib/Basic/Targets.cpp
+++ cfe/trunk/lib/Basic/Targets.cpp
@@ -6672,6 +6672,19 @@
   NumAliases = 0;
 }
 
+// We attempt to use PNaCl (le32) frontend and Mips32EL backend.
+class NaClMips32ELTargetInfo : public Mips32ELTargetInfo {
+public:
+  NaClMips32ELTargetInfo(const llvm::Triple &Triple) :
+    Mips32ELTargetInfo(Triple)  {
+      MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 0;
+  }
+
+  BuiltinVaListKind getBuiltinVaListKind() const override {
+    return TargetInfo::PNaClABIBuiltinVaList;
+  }
+};
+
 class Le64TargetInfo : public TargetInfo {
   static const Builtin::Info BuiltinInfo[];
 
@@ -7042,7 +7055,7 @@
     case llvm::Triple::NetBSD:
       return new NetBSDTargetInfo<Mips32ELTargetInfo>(Triple);
     case llvm::Triple::NaCl:
-      return new NaClTargetInfo<Mips32ELTargetInfo>(Triple);
+      return new NaClTargetInfo<NaClMips32ELTargetInfo>(Triple);
     default:
       return new Mips32ELTargetInfo(Triple);
     }
Index: cfe/trunk/lib/CodeGen/TargetInfo.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/TargetInfo.cpp
+++ cfe/trunk/lib/CodeGen/TargetInfo.cpp
@@ -7099,6 +7099,8 @@
     return *(TheTargetCodeGenInfo = new PNaClTargetCodeGenInfo(Types));
   case llvm::Triple::mips:
   case llvm::Triple::mipsel:
+    if (Triple.getOS() == llvm::Triple::NaCl)
+      return *(TheTargetCodeGenInfo = new PNaClTargetCodeGenInfo(Types));
     return *(TheTargetCodeGenInfo = new MIPSTargetCodeGenInfo(Types, true));
 
   case llvm::Triple::mips64:
Index: cfe/trunk/lib/Driver/ToolChains.h
===================================================================
--- cfe/trunk/lib/Driver/ToolChains.h
+++ cfe/trunk/lib/Driver/ToolChains.h
@@ -747,7 +747,9 @@
   void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
                            llvm::opt::ArgStringList &CmdArgs) const override;
 
-  bool IsIntegratedAssemblerDefault() const override { return false; }
+  bool IsIntegratedAssemblerDefault() const override {
+    return getTriple().getArch() == llvm::Triple::mipsel;
+  }
 
   // Get the path to the file containing NaCl's ARM macros. It lives in NaCl_TC
   // because the AssembleARM tool needs a const char * that it can pass around
Index: cfe/trunk/lib/Driver/ToolChains.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains.cpp
+++ cfe/trunk/lib/Driver/ToolChains.cpp
@@ -2337,6 +2337,13 @@
     file_paths.push_back(ToolPath + "arm-nacl");
     break;
   }
+  case llvm::Triple::mipsel: {
+    file_paths.push_back(FilePath + "mipsel-nacl/lib");
+    file_paths.push_back(FilePath + "mipsel-nacl/usr/lib");
+    prog_paths.push_back(ProgPath + "bin");
+    file_paths.push_back(ToolPath + "mipsel-nacl");
+    break;
+  }
   default:
     break;
   }
@@ -2372,6 +2379,9 @@
   case llvm::Triple::x86_64:
     llvm::sys::path::append(P, "x86_64-nacl/usr/include");
     break;
+  case llvm::Triple::mipsel:
+    llvm::sys::path::append(P, "mipsel-nacl/usr/include");
+    break;
   default:
     return;
   }
@@ -2416,6 +2426,10 @@
     llvm::sys::path::append(P, "x86_64-nacl/include/c++/v1");
     addSystemInclude(DriverArgs, CC1Args, P.str());
     break;
+  case llvm::Triple::mipsel:
+    llvm::sys::path::append(P, "mipsel-nacl/include/c++/v1");
+    addSystemInclude(DriverArgs, CC1Args, P.str());
+    break;
   default:
     break;
   }
Index: cfe/trunk/lib/Driver/Tools.cpp
===================================================================
--- cfe/trunk/lib/Driver/Tools.cpp
+++ cfe/trunk/lib/Driver/Tools.cpp
@@ -8200,6 +8200,8 @@
     CmdArgs.push_back("armelf_nacl");
   else if (Arch == llvm::Triple::x86_64)
     CmdArgs.push_back("elf_x86_64_nacl");
+  else if (Arch == llvm::Triple::mipsel)
+    CmdArgs.push_back("mipselelf_nacl");
   else
     D.Diag(diag::err_target_unsupported_arch) << ToolChain.getArchName()
                                               << "Native Client";
@@ -8261,6 +8263,13 @@
       // in the group for C++.
       if (Args.hasArg(options::OPT_pthread) ||
           Args.hasArg(options::OPT_pthreads) || D.CCCIsCXX()) {
+        // Gold, used by Mips, handles nested groups differently than ld, and
+        // without '-lnacl' it prefers symbols from libpthread.a over libnacl.a,
+        // which is not a desired behaviour here.
+        // See https://sourceware.org/ml/binutils/2015-03/msg00034.html
+        if (getToolChain().getArch() == llvm::Triple::mipsel)
+          CmdArgs.push_back("-lnacl");
+
         CmdArgs.push_back("-lpthread");
       }
 
@@ -8271,6 +8280,13 @@
       else
         CmdArgs.push_back("-lgcc_s");
       CmdArgs.push_back("--no-as-needed");
+
+      // Mips needs to create and use pnacl_legacy library that contains
+      // definitions from bitcode/pnaclmm.c and definitions for
+      // __nacl_tp_tls_offset() and __nacl_tp_tdb_offset().
+      if (getToolChain().getArch() == llvm::Triple::mipsel)
+        CmdArgs.push_back("-lpnacl_legacy");
+
       CmdArgs.push_back("--end-group");
     }
 
Index: cfe/trunk/test/Driver/nacl-direct.c
===================================================================
--- cfe/trunk/test/Driver/nacl-direct.c
+++ cfe/trunk/test/Driver/nacl-direct.c
@@ -63,6 +63,29 @@
 // CHECK-ARM: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}arm-nacl{{/|\\\\}}usr{{/|\\\\}}lib"
 // CHECK-ARM: "-Lfoo{{/|\\\\}}lib{{/|\\\\}}arm-nacl"
 // CHECK-ARM-NOT: -lpthread
+//
+// RUN: %clang -no-canonical-prefixes -### -o %t.o %s \
+// RUN:     -target mipsel-unknown-nacl -resource-dir foo 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MIPS %s
+// CHECK-MIPS: {{.*}}clang{{.*}}" "-cc1"
+// CHECK-MIPS: "-fuse-init-array"
+// CHECK-MIPS: "-target-cpu" "mips32r2"
+// CHECK-MIPS: "-target-abi" "o32"
+// CHECK-MIPS: "-mfloat-abi" "hard"
+// CHECK-MIPS: "-resource-dir" "foo"
+// CHECK-MIPS: "-internal-isystem" "foo{{/|\\\\}}include"
+// CHECK-MIPS: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}mipsel-nacl{{/|\\\\}}usr{{/|\\\\}}include"
+// CHECK-MIPS: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}mipsel-nacl{{/|\\\\}}include"
+// CHECK-MIPS-NOT: as{{(.exe)?}}"
+// CHECK-MIPS: ld{{(.exe)?}}"
+// CHECK-MIPS: "--build-id"
+// CHECK-MIPS: "-m" "mipselelf_nacl"
+// CHECK-MIPS: "-static"
+// CHECK-MIPS: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}mipsel-nacl{{/|\\\\}}lib"
+// CHECK-MIPS: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}mipsel-nacl{{/|\\\\}}usr{{/|\\\\}}lib"
+// CHECK-MIPS: "-Lfoo{{/|\\\\}}lib{{/|\\\\}}mipsel-nacl"
+// CHECK-MIPS: "-lpnacl_legacy"
+// CHECK-MIPS-NOT: "-lpthread"
 
 // Check that even when the target arch is just "arm" (as will be the case when
 // it is inferred from the binary name) that we get the right ABI flags
@@ -109,3 +132,15 @@
 // CHECK-x86_64-CXX: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}x86_64-nacl{{/|\\\\}}usr{{/|\\\\}}include"
 // CHECK-x86_64-CXX: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}x86_64-nacl{{/|\\\\}}include"
 // CHECK-x86_64-CXX: "-lpthread"
+
+// RUN: %clangxx -no-canonical-prefixes -### -o %t.o %s \
+// RUN:     -target mipsel-unknown-nacl -resource-dir foo 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MIPS-CXX %s
+// CHECK-MIPS-CXX: {{.*}}clang{{.*}}" "-cc1"
+// CHECK-MIPS-CXX: "-resource-dir" "foo"
+// CHECK-MIPS-CXX: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}mipsel-nacl{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
+// CHECK-MIPS-CXX: "-internal-isystem" "foo{{/|\\\\}}include"
+// CHECK-MIPS-CXX: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}mipsel-nacl{{/|\\\\}}usr{{/|\\\\}}include"
+// CHECK-MIPS-CXX: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}mipsel-nacl{{/|\\\\}}include"
+// CHECK-MIPS-CXX: "-lnacl"
+// CHECK-MIPS-CXX: "-lpthread"