Index: lib/Support/Triple.cpp
===================================================================
--- lib/Support/Triple.cpp
+++ lib/Support/Triple.cpp
@@ -1556,7 +1556,7 @@
 
     if (NewEnv != T.getEnvironment())
       T.setEnvironment(NewEnv);
-    return std::make_pair(T, "");
+    return std::make_pair(T, ABI);
   }
   }
 }
Index: lib/Target/Mips/MCTargetDesc/MipsABIInfo.cpp
===================================================================
--- lib/Target/Mips/MCTargetDesc/MipsABIInfo.cpp
+++ lib/Target/Mips/MCTargetDesc/MipsABIInfo.cpp
@@ -49,9 +49,25 @@
 
 MipsABIInfo MipsABIInfo::computeTargetABI(const Triple &TT, StringRef CPU,
                                           const MCTargetOptions &Options) {
-  if (!Options.getABIName().empty())
-    llvm_unreachable(
-        "ABI name should be in triple. See Triple::getABIVariant()");
+  if (Options.getABIName().startswith("o32")) {
+    assert((TT.getEnvironment() == Triple::ABI32 ||
+            TT.getEnvironment() == Triple::AndroidABI32 ||
+            TT.getEnvironment() == Triple::GNUABI32) &&
+           "Selected ABI disagrees with triple");
+    return MipsABIInfo::O32();
+  } else if (Options.getABIName().startswith("n32")) {
+    assert((TT.getEnvironment() == Triple::ABIN32 ||
+            TT.getEnvironment() == Triple::GNUABIN32) &&
+           "Selected ABI disagrees with triple");
+    return MipsABIInfo::N32();
+  } else if (Options.getABIName().startswith("n64")) {
+    assert((TT.getEnvironment() == Triple::ABI64 ||
+            TT.getEnvironment() == Triple::AndroidABI64 ||
+            TT.getEnvironment() == Triple::GNUABI64) &&
+           "Selected ABI disagrees with triple");
+    return MipsABIInfo::N64();
+  } else if (!Options.getABIName().empty())
+    llvm_unreachable("Unknown ABI option for MIPS");
   else if (TT.getEnvironment() == Triple::ABI32 ||
            TT.getEnvironment() == Triple::AndroidABI32 ||
            TT.getEnvironment() == Triple::GNUABI32)
Index: unittests/ADT/TripleTest.cpp
===================================================================
--- unittests/ADT/TripleTest.cpp
+++ unittests/ADT/TripleTest.cpp
@@ -868,10 +868,13 @@
     EXPECT_EQ(Triple::GNUABIN32, N32.first.getEnvironment());
     EXPECT_EQ(Triple::GNUABI64, N64.first.getEnvironment());
 
-    EXPECT_EQ("", Default.second);
-    EXPECT_EQ("", O32.second);
-    EXPECT_EQ("", N32.second);
-    EXPECT_EQ("", N64.second);
+    EXPECT_EQ((T.getArch() == Triple::mips64 || T.getArch() == Triple::mips64el)
+                  ? "n64"
+                  : "o32",
+              Default.second);
+    EXPECT_EQ("o32", O32.second);
+    EXPECT_EQ("n32", N32.second);
+    EXPECT_EQ("n64", N64.second);
 
     // Try an unsupported ABI name. This should change the arch component of the
     // triple to UnknownArch. Other values are undefined.
@@ -906,9 +909,12 @@
     EXPECT_EQ(Triple::AndroidABI32, O32.first.getEnvironment());
     EXPECT_EQ(Triple::AndroidABI64, N64.first.getEnvironment());
 
-    EXPECT_EQ("", Default.second);
-    EXPECT_EQ("", O32.second);
-    EXPECT_EQ("", N64.second);
+    EXPECT_EQ((T.getArch() == Triple::mips64 || T.getArch() == Triple::mips64el)
+                  ? "n64"
+                  : "o32",
+              Default.second);
+    EXPECT_EQ("o32", O32.second);
+    EXPECT_EQ("n64", N64.second);
 
     // Try an unsupported ABI name. This should change the arch component of the
     // triple to UnknownArch. Other values are undefined.
@@ -954,10 +960,13 @@
     EXPECT_EQ(Triple::ABIN32, N32.first.getEnvironment());
     EXPECT_EQ(Triple::ABI64, N64.first.getEnvironment());
 
-    EXPECT_EQ("", Default.second);
-    EXPECT_EQ("", O32.second);
-    EXPECT_EQ("", N32.second);
-    EXPECT_EQ("", N64.second);
+    EXPECT_EQ((T.getArch() == Triple::mips64 || T.getArch() == Triple::mips64el)
+                  ? "n64"
+                  : "o32",
+              Default.second);
+    EXPECT_EQ("o32", O32.second);
+    EXPECT_EQ("n32", N32.second);
+    EXPECT_EQ("n64", N64.second);
     EXPECT_EQ("foo", Foo.second);
   }
 }