Index: ADT/TripleTest.cpp
===================================================================
--- ADT/TripleTest.cpp
+++ ADT/TripleTest.cpp
@@ -1000,6 +1000,15 @@
   EXPECT_EQ((unsigned)7, Major);
   EXPECT_EQ((unsigned)0, Minor);
   EXPECT_EQ((unsigned)0, Micro);
+  EXPECT_FALSE(T.isSimulatorEnvironment());
+
+  T = Triple("x86_64-apple-ios10.3-simulator");
+  EXPECT_TRUE(T.isiOS());
+  T.getiOSVersion(Major, Minor, Micro);
+  EXPECT_EQ((unsigned)10, Major);
+  EXPECT_EQ((unsigned)3, Minor);
+  EXPECT_EQ((unsigned)0, Micro);
+  EXPECT_TRUE(T.isSimulatorEnvironment());
 }
 
 TEST(TripleTest, FileFormat) {
Index: Support/Triple.cpp
===================================================================
--- Support/Triple.cpp
+++ Support/Triple.cpp
@@ -235,6 +235,7 @@
   case AMDOpenCL: return "amdopencl";
   case CoreCLR: return "coreclr";
   case OpenCL: return "opencl";
+  case Simulator: return "simulator";
   }
 
   llvm_unreachable("Invalid EnvironmentType!");
@@ -525,6 +526,7 @@
     .StartsWith("amdopencl", Triple::AMDOpenCL)
     .StartsWith("coreclr", Triple::CoreCLR)
     .StartsWith("opencl", Triple::OpenCL)
+    .StartsWith("simulator", Triple::Simulator)
     .Default(Triple::UnknownEnvironment);
 }
 
Index: llvm/ADT/Triple.h
===================================================================
--- llvm/ADT/Triple.h
+++ llvm/ADT/Triple.h
@@ -205,7 +205,8 @@
     AMDOpenCL,
     CoreCLR,
     OpenCL,
-    LastEnvironmentType = OpenCL
+    Simulator,  // Simulator variants of other systems, e.g., Apple's iOS
+    LastEnvironmentType = Simulator
   };
   enum ObjectFormatType {
     UnknownObjectFormat,
@@ -470,6 +471,10 @@
     return isMacOSX() || isiOS() || isWatchOS();
   }
 
+  bool isSimulatorEnvironment() const {
+    return getEnvironment() == Triple::Simulator;
+  }
+
   bool isOSNetBSD() const {
     return getOS() == Triple::NetBSD;
   }