Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -5696,14 +5696,6 @@
   }
   const std::string& getCPU() const { return CPU; }
   void getDefaultFeatures(llvm::StringMap<bool> &Features) const override {
-    // The backend enables certain ABI's by default according to the
-    // architecture.
-    // Disable both possible defaults so that we don't end up with multiple
-    // ABI's selected and trigger an assertion.
-    Features["o32"] = false;
-    Features["n64"] = false;
-
-    Features[ABI] = true;
     if (CPU == "octeon")
       Features["mips64r2"] = Features["cnmips"] = true;
     else
Index: lib/Driver/Tools.h
===================================================================
--- lib/Driver/Tools.h
+++ lib/Driver/Tools.h
@@ -109,7 +109,8 @@
     ClangAs(const ToolChain &TC) : Tool("clang::as",
                                         "clang integrated assembler", TC,
                                         RF_Full) {}
-
+    void AddMIPSTargetArgs(const llvm::opt::ArgList &Args,
+                           llvm::opt::ArgStringList &CmdArgs) const;
     bool hasGoodDiagnostics() const override { return true; }
     bool hasIntegratedAssembler() const override { return false; }
     bool hasIntegratedCPP() const override { return false; }
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -1095,17 +1095,6 @@
   mips::getMipsCPUAndABI(Args, Triple, CPUName, ABIName);
   ABIName = getGnuCompatibleMipsABIName(ABIName);
 
-  // Always override the backend's default ABI.
-  std::string ABIFeature = llvm::StringSwitch<StringRef>(ABIName)
-                               .Case("32", "+o32")
-                               .Case("n32", "+n32")
-                               .Case("64", "+n64")
-                               .Case("eabi", "+eabi")
-                               .Default(("+" + ABIName).str());
-  Features.push_back("-o32");
-  Features.push_back("-n64");
-  Features.push_back(Args.MakeArgString(ABIFeature));
-
   AddTargetFeature(Args, Features, options::OPT_mno_abicalls,
                    options::OPT_mabicalls, "noabicalls");
 
@@ -4875,6 +4864,17 @@
   return CLFallback.get();
 }
 
+void ClangAs::AddMIPSTargetArgs(const ArgList &Args,
+                              ArgStringList &CmdArgs) const {
+  StringRef CPUName;
+  StringRef ABIName;
+  const llvm::Triple &Triple = getToolChain().getTriple();
+  mips::getMipsCPUAndABI(Args, Triple, CPUName, ABIName);
+
+  CmdArgs.push_back("-target-abi");
+  CmdArgs.push_back(ABIName.data());
+}
+
 void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,
                            const InputInfo &Output,
                            const InputInfoList &Inputs,
@@ -4982,6 +4982,19 @@
 
   // FIXME: Add -static support, once we have it.
 
+    // Add target specific flags.
+  switch(getToolChain().getArch()) {
+  default:
+    break;
+
+  case llvm::Triple::mips:
+  case llvm::Triple::mipsel:
+  case llvm::Triple::mips64:
+  case llvm::Triple::mips64el:
+    AddMIPSTargetArgs(Args, CmdArgs);
+    break;
+  }
+
   // Consume all the warning flags. Usually this would be handled more
   // gracefully by -cc1 (warning about unknown warning flags, etc) but -cc1as
   // doesn't handle that so rather than warning about unused flags that are
Index: test/Driver/mips-integrated-as.s
===================================================================
--- test/Driver/mips-integrated-as.s
+++ test/Driver/mips-integrated-as.s
@@ -5,24 +5,19 @@
 // RUN: %clang -target mips-linux-gnu -### -fintegrated-as -c %s -mabi=o32 2>&1 | \
 // RUN:   FileCheck -check-prefix=ABI-O32 %s
 // ABI-O32: -cc1as
-// ABI-O32: "-target-feature" "-n64"
-// ABI-O32: "-target-feature" "+o32"
+// ABI-O32: "-target-abi" "o32"
 
 // RUN: %clang -target mips-linux-gnu -### -fintegrated-as -c %s -mabi=eabi 2>&1 | \
 // RUN:   FileCheck -check-prefix=ABI-EABI32 %s
 // ABI-EABI32: -cc1as
-// ABI-EABI32: "-target-feature" "-o32"
-// ABI-EABI32: "-target-feature" "-n64"
-// ABI-EABI32: "-target-feature" "+eabi"
+// ABI-EABI32: "-target-abi" "eabi"
 
 // RUN: %clang -target mips-linux-gnu -### -fintegrated-as -c %s -mips64 -mabi=n32 2>&1 | \
 // RUN:   FileCheck -check-prefix=ABI-N32 %s
 // RUN: %clang -target mips64-linux-gnu -### -fintegrated-as -c %s -mabi=n32 2>&1 | \
 // RUN:   FileCheck -check-prefix=ABI-N32 %s
 // ABI-N32: -cc1as
-// ABI-N32: "-target-feature" "-o32"
-// ABI-N32: "-target-feature" "-n64"
-// ABI-N32: "-target-feature" "+n32"
+// ABI-N32: "-target-abi" "n32"
 
 // FIXME: We should also test '-target mips-linux-gnu -mips64' defaults to the
 //        default 64-bit ABI (N64 but GCC uses N32). It currently selects O32
@@ -39,8 +34,7 @@
 // RUN: %clang -target mips64-linux-gnu -### -fintegrated-as -c %s -mips64 -mabi=n64 2>&1 | \
 // RUN:   FileCheck -check-prefix=ABI-N64 %s
 // ABI-N64: -cc1as
-// ABI-N64: "-target-feature" "-o32"
-// ABI-N64: "-target-feature" "+n64"
+// ABI-N64: "-target-abi" "n64"
 
 // RUN: %clang -target mips-linux-gnu -### -fintegrated-as -c %s -msoft-float 2>&1 | \
 // RUN:   FileCheck -check-prefix=SOFTFLOAT %s