diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -634,36 +634,38 @@
 
   // If target is MIPS adjust the target triple
   // accordingly to provided ABI name.
-  A = Args.getLastArg(options::OPT_mabi_EQ);
-  if (A && Target.isMIPS()) {
-    StringRef ABIName = A->getValue();
-    if (ABIName == "32") {
-      Target = Target.get32BitArchVariant();
-      if (Target.getEnvironment() == llvm::Triple::GNUABI64 ||
-          Target.getEnvironment() == llvm::Triple::GNUABIN32)
-        Target.setEnvironment(llvm::Triple::GNU);
-    } else if (ABIName == "n32") {
-      Target = Target.get64BitArchVariant();
-      if (Target.getEnvironment() == llvm::Triple::GNU ||
-          Target.getEnvironment() == llvm::Triple::GNUABI64)
-        Target.setEnvironment(llvm::Triple::GNUABIN32);
-    } else if (ABIName == "64") {
-      Target = Target.get64BitArchVariant();
-      if (Target.getEnvironment() == llvm::Triple::GNU ||
-          Target.getEnvironment() == llvm::Triple::GNUABIN32)
-        Target.setEnvironment(llvm::Triple::GNUABI64);
+  if (Target.isMIPS()) {
+    if (A = Args.getLastArg(options::OPT_mabi_EQ)) {
+      StringRef ABIName = A->getValue();
+      if (ABIName == "32") {
+        Target = Target.get32BitArchVariant();
+        if (Target.getEnvironment() == llvm::Triple::GNUABI64 ||
+            Target.getEnvironment() == llvm::Triple::GNUABIN32)
+          Target.setEnvironment(llvm::Triple::GNU);
+      } else if (ABIName == "n32") {
+        Target = Target.get64BitArchVariant();
+        if (Target.getEnvironment() == llvm::Triple::GNU ||
+            Target.getEnvironment() == llvm::Triple::GNUABI64)
+          Target.setEnvironment(llvm::Triple::GNUABIN32);
+      } else if (ABIName == "64") {
+        Target = Target.get64BitArchVariant();
+        if (Target.getEnvironment() == llvm::Triple::GNU ||
+            Target.getEnvironment() == llvm::Triple::GNUABIN32)
+          Target.setEnvironment(llvm::Triple::GNUABI64);
+      }
     }
   }
 
   // If target is RISC-V adjust the target triple according to
   // provided architecture name
-  A = Args.getLastArg(options::OPT_march_EQ);
-  if (A && Target.isRISCV()) {
-    StringRef ArchName = A->getValue();
-    if (ArchName.startswith_insensitive("rv32"))
-      Target.setArch(llvm::Triple::riscv32);
-    else if (ArchName.startswith_insensitive("rv64"))
-      Target.setArch(llvm::Triple::riscv64);
+  if (Target.isRISCV()) {
+    if (A = Args.getLastArg(options::OPT_march_EQ)) {
+      StringRef ArchName = A->getValue();
+      if (ArchName.startswith_insensitive("rv32"))
+        Target.setArch(llvm::Triple::riscv32);
+      else if (ArchName.startswith_insensitive("rv64"))
+        Target.setArch(llvm::Triple::riscv64);
+    }
   }
 
   return Target;
diff --git a/clang/test/Driver/mabi.c b/clang/test/Driver/mabi.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/mabi.c
@@ -0,0 +1,6 @@
+// RUN: %clang --target=i386-unknown-linux -mabi=ms -S %s -### 2>&1 | FileCheck --check-prefix=CHECK %s
+
+int f() {
+  // CHECK: warning: argument unused during compilation: '-mabi=ms'
+  return 0;
+}