Index: llvm/trunk/include/llvm/ADT/Triple.h
===================================================================
--- llvm/trunk/include/llvm/ADT/Triple.h
+++ llvm/trunk/include/llvm/ADT/Triple.h
@@ -174,7 +174,8 @@
     Cygnus,
     AMDOpenCL,
     CoreCLR,
-    LastEnvironmentType = CoreCLR
+    ELFIAMCU,
+    LastEnvironmentType = ELFIAMCU
   };
   enum ObjectFormatType {
     UnknownObjectFormat,
@@ -431,6 +432,10 @@
     return getOS() == Triple::Bitrig;
   }
 
+  bool isEnvironmentIAMCU() const {
+    return getEnvironment() == Triple::ELFIAMCU;
+  }
+
   bool isWindowsMSVCEnvironment() const {
     return getOS() == Triple::Win32 &&
            (getEnvironment() == Triple::UnknownEnvironment ||
Index: llvm/trunk/lib/Support/Triple.cpp
===================================================================
--- llvm/trunk/lib/Support/Triple.cpp
+++ llvm/trunk/lib/Support/Triple.cpp
@@ -202,6 +202,7 @@
   case Cygnus: return "cygnus";
   case AMDOpenCL: return "amdopencl";
   case CoreCLR: return "coreclr";
+  case ELFIAMCU: return "elfiamcu";
   }
 
   llvm_unreachable("Invalid EnvironmentType!");
@@ -453,6 +454,7 @@
     .StartsWith("cygnus", Triple::Cygnus)
     .StartsWith("amdopencl", Triple::AMDOpenCL)
     .StartsWith("coreclr", Triple::CoreCLR)
+    .StartsWith("elfiamcu", Triple::ELFIAMCU)
     .Default(Triple::UnknownEnvironment);
 }
 
Index: llvm/trunk/lib/Target/X86/X86Subtarget.h
===================================================================
--- llvm/trunk/lib/Target/X86/X86Subtarget.h
+++ llvm/trunk/lib/Target/X86/X86Subtarget.h
@@ -418,6 +418,7 @@
   bool isTargetNaCl() const { return TargetTriple.isOSNaCl(); }
   bool isTargetNaCl32() const { return isTargetNaCl() && !is64Bit(); }
   bool isTargetNaCl64() const { return isTargetNaCl() && is64Bit(); }
+  bool isTargetMCU() const { return TargetTriple.isEnvironmentIAMCU(); }
 
   bool isTargetWindowsMSVC() const {
     return TargetTriple.isWindowsMSVCEnvironment();
Index: llvm/trunk/unittests/ADT/TripleTest.cpp
===================================================================
--- llvm/trunk/unittests/ADT/TripleTest.cpp
+++ llvm/trunk/unittests/ADT/TripleTest.cpp
@@ -81,6 +81,12 @@
   EXPECT_EQ(Triple::Darwin, T.getOS());
   EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
 
+  T = Triple("i386-pc-linux-elfiamcu");
+  EXPECT_EQ(Triple::x86, T.getArch());
+  EXPECT_EQ(Triple::PC, T.getVendor());
+  EXPECT_EQ(Triple::Linux, T.getOS());
+  EXPECT_EQ(Triple::ELFIAMCU, T.getEnvironment());
+
   T = Triple("x86_64-pc-linux-gnu");
   EXPECT_EQ(Triple::x86_64, T.getArch());
   EXPECT_EQ(Triple::PC, T.getVendor());