Index: include/clang/Basic/BuiltinsWebAssembly.def
===================================================================
--- include/clang/Basic/BuiltinsWebAssembly.def
+++ include/clang/Basic/BuiltinsWebAssembly.def
@@ -21,4 +21,8 @@
 BUILTIN(__builtin_wasm_current_memory, "z", "n")
 BUILTIN(__builtin_wasm_grow_memory, "zz", "n")
 
+// Exception handling builtins.
+BUILTIN(__builtin_wasm_throw, "vUiv*", "r")
+BUILTIN(__builtin_wasm_rethrow, "v", "r")
+
 #undef BUILTIN
Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp
+++ lib/CodeGen/CGBuiltin.cpp
@@ -9372,6 +9372,16 @@
     Value *Callee = CGM.getIntrinsic(Intrinsic::wasm_grow_memory, X->getType());
     return Builder.CreateCall(Callee, X);
   }
+  case WebAssembly::BI__builtin_wasm_throw: {
+    Value *Tag = EmitScalarExpr(E->getArg(0));
+    Value *Obj = EmitScalarExpr(E->getArg(1));
+    Value *Callee = CGM.getIntrinsic(Intrinsic::wasm_throw);
+    return Builder.CreateCall(Callee, {Tag, Obj});
+  }
+  case WebAssembly::BI__builtin_wasm_rethrow: {
+    Value *Callee = CGM.getIntrinsic(Intrinsic::wasm_rethrow);
+    return Builder.CreateCall(Callee);
+  }
 
   default:
     return nullptr;
Index: test/CodeGen/builtins-wasm.c
===================================================================
--- test/CodeGen/builtins-wasm.c
+++ test/CodeGen/builtins-wasm.c
@@ -14,3 +14,15 @@
 // WEBASSEMBLY32: call i32 @llvm.wasm.grow.memory.i32(i32 %{{.*}})
 // WEBASSEMBLY64: call i64 @llvm.wasm.grow.memory.i64(i64 %{{.*}})
 }
+
+void f3(unsigned int tag, void *obj) {
+  return __builtin_wasm_throw(tag, obj);
+// WEBASSEMBLY32: call void @llvm.wasm.throw(i32 %{{.*}}, i8* %{{.*}})
+// WEBASSEMBLY64: call void @llvm.wasm.throw(i32 %{{.*}}, i8* %{{.*}})
+}
+
+void f4() {
+  return __builtin_wasm_rethrow();
+// WEBASSEMBLY32: call void @llvm.wasm.rethrow()
+// WEBASSEMBLY64: call void @llvm.wasm.rethrow()
+}