Index: llvm/trunk/include/llvm/ADT/Triple.h
===================================================================
--- llvm/trunk/include/llvm/ADT/Triple.h
+++ llvm/trunk/include/llvm/ADT/Triple.h
@@ -187,7 +187,8 @@
     AMDPAL,     // AMD PAL Runtime
     HermitCore, // HermitCore Unikernel/Multikernel
     Hurd,       // GNU/Hurd
-    LastOSType = Hurd
+    COWS,       // Capability-Oriented WebAssembly Syscalls
+    LastOSType = COWS
   };
   enum EnvironmentType {
     UnknownEnvironment,
@@ -588,6 +589,11 @@
     return getOS() == Triple::Hurd;
   }
 
+  /// Tests whether the OS is COWS.
+  bool isOSCOWS() const {
+    return getOS() == Triple::COWS;
+  }
+
   /// Tests whether the OS uses glibc.
   bool isOSGlibc() const {
     return (getOS() == Triple::Linux || getOS() == Triple::KFreeBSD ||
Index: llvm/trunk/lib/Support/Triple.cpp
===================================================================
--- llvm/trunk/lib/Support/Triple.cpp
+++ llvm/trunk/lib/Support/Triple.cpp
@@ -211,6 +211,7 @@
   case AMDPAL: return "amdpal";
   case HermitCore: return "hermit";
   case Hurd: return "hurd";
+  case COWS: return "cows";
   }
 
   llvm_unreachable("Invalid OSType");
@@ -510,6 +511,7 @@
     .StartsWith("amdpal", Triple::AMDPAL)
     .StartsWith("hermit", Triple::HermitCore)
     .StartsWith("hurd", Triple::Hurd)
+    .StartsWith("cows", Triple::COWS)
     .Default(Triple::UnknownOS);
 }
 
Index: llvm/trunk/unittests/ADT/TripleTest.cpp
===================================================================
--- llvm/trunk/unittests/ADT/TripleTest.cpp
+++ llvm/trunk/unittests/ADT/TripleTest.cpp
@@ -253,12 +253,24 @@
   EXPECT_EQ(Triple::UnknownOS, T.getOS());
   EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
 
+  T = Triple("wasm32-unknown-cows-musl");
+  EXPECT_EQ(Triple::wasm32, T.getArch());
+  EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
+  EXPECT_EQ(Triple::COWS, T.getOS());
+  EXPECT_EQ(Triple::Musl, T.getEnvironment());
+
   T = Triple("wasm64-unknown-unknown");
   EXPECT_EQ(Triple::wasm64, T.getArch());
   EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
   EXPECT_EQ(Triple::UnknownOS, T.getOS());
   EXPECT_EQ(Triple::UnknownEnvironment, T.getEnvironment());
 
+  T = Triple("wasm64-unknown-cows-musl");
+  EXPECT_EQ(Triple::wasm64, T.getArch());
+  EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
+  EXPECT_EQ(Triple::COWS, T.getOS());
+  EXPECT_EQ(Triple::Musl, T.getEnvironment());
+
   T = Triple("avr-unknown-unknown");
   EXPECT_EQ(Triple::avr, T.getArch());
   EXPECT_EQ(Triple::UnknownVendor, T.getVendor());
@@ -1235,11 +1247,17 @@
 
   EXPECT_EQ(Triple::Wasm, Triple("wasm32-unknown-unknown").getObjectFormat());
   EXPECT_EQ(Triple::Wasm, Triple("wasm64-unknown-unknown").getObjectFormat());
+  EXPECT_EQ(Triple::Wasm, Triple("wasm32-unknown-cows-musl").getObjectFormat());
+  EXPECT_EQ(Triple::Wasm, Triple("wasm64-unknown-cows-musl").getObjectFormat());
 
   EXPECT_EQ(Triple::Wasm,
             Triple("wasm32-unknown-unknown-wasm").getObjectFormat());
   EXPECT_EQ(Triple::Wasm,
             Triple("wasm64-unknown-unknown-wasm").getObjectFormat());
+  EXPECT_EQ(Triple::Wasm,
+            Triple("wasm32-unknown-cows-musl-wasm").getObjectFormat());
+  EXPECT_EQ(Triple::Wasm,
+            Triple("wasm64-unknown-cows-musl-wasm").getObjectFormat());
 
   Triple MSVCNormalized(Triple::normalize("i686-pc-windows-msvc-elf"));
   EXPECT_EQ(Triple::ELF, MSVCNormalized.getObjectFormat());