Index: include/clang/Basic/BuiltinsWebAssembly.def
===================================================================
--- include/clang/Basic/BuiltinsWebAssembly.def
+++ include/clang/Basic/BuiltinsWebAssembly.def
@@ -34,4 +34,9 @@
 BUILTIN(__builtin_wasm_throw, "vUiv*", "r")
 BUILTIN(__builtin_wasm_rethrow, "v", "r")
 
+// Atomic wait and wake.
+BUILTIN(__builtin_wasm_atomic_wait_i32, "Uiv*iLLi", "n")
+BUILTIN(__builtin_wasm_atomic_wait_i64, "Uiv*LLiLLi", "n")
+BUILTIN(__builtin_wasm_atomic_wake, "ULLiv*LLi", "n")
+
 #undef BUILTIN
Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp
+++ lib/CodeGen/CGBuiltin.cpp
@@ -12054,6 +12054,26 @@
     Value *Callee = CGM.getIntrinsic(Intrinsic::wasm_rethrow);
     return Builder.CreateCall(Callee);
   }
+  case WebAssembly::BI__builtin_wasm_atomic_wait_i32: {
+    Value *Addr = EmitScalarExpr(E->getArg(0));
+    Value *Expected = EmitScalarExpr(E->getArg(1));
+    Value *Timeout = EmitScalarExpr(E->getArg(2));
+    Value *Callee = CGM.getIntrinsic(Intrinsic::wasm_atomic_wait_i32);
+    return Builder.CreateCall(Callee, {Addr, Expected, Timeout});
+  }
+  case WebAssembly::BI__builtin_wasm_atomic_wait_i64: {
+    Value *Addr = EmitScalarExpr(E->getArg(0));
+    Value *Expected = EmitScalarExpr(E->getArg(1));
+    Value *Timeout = EmitScalarExpr(E->getArg(2));
+    Value *Callee = CGM.getIntrinsic(Intrinsic::wasm_atomic_wait_i64);
+    return Builder.CreateCall(Callee, {Addr, Expected, Timeout});
+  }
+  case WebAssembly::BI__builtin_wasm_atomic_wake: {
+    Value *Addr = EmitScalarExpr(E->getArg(0));
+    Value *WakeCount = EmitScalarExpr(E->getArg(1));
+    Value *Callee = CGM.getIntrinsic(Intrinsic::wasm_atomic_wake);
+    return Builder.CreateCall(Callee, {Addr, WakeCount});
+  }
 
   default:
     return nullptr;
Index: test/CodeGen/builtins-wasm.c
===================================================================
--- test/CodeGen/builtins-wasm.c
+++ test/CodeGen/builtins-wasm.c
@@ -50,3 +50,21 @@
 // WEBASSEMBLY32: call void @llvm.wasm.rethrow()
 // WEBASSEMBLY64: call void @llvm.wasm.rethrow()
 }
+
+unsigned int f8(void *addr, int expected, long long timeout) {
+  return __builtin_wasm_atomic_wait_i32(addr, expected, timeout);
+// WEBASSEMBLY32: call i32 @llvm.wasm.atomic.wait.i32(i8* %{{.*}}, i32 %{{.*}}, i64 %{{.*}})
+// WEBASSEMBLY64: call i32 @llvm.wasm.atomic.wait.i32(i8* %{{.*}}, i32 %{{.*}}, i64 %{{.*}})
+}
+
+unsigned int f9(void *addr, long long expected, long long timeout) {
+  return __builtin_wasm_atomic_wait_i64(addr, expected, timeout);
+// WEBASSEMBLY32: call i32 @llvm.wasm.atomic.wait.i64(i8* %{{.*}}, i64 %{{.*}}, i64 %{{.*}})
+// WEBASSEMBLY64: call i32 @llvm.wasm.atomic.wait.i64(i8* %{{.*}}, i64 %{{.*}}, i64 %{{.*}})
+}
+
+unsigned long long f10(void *addr, long long wake_count) {
+  return __builtin_wasm_atomic_wake(addr, wake_count);
+// WEBASSEMBLY32: call i64 @llvm.wasm.atomic.wake(i8* %{{.*}}, i64 %{{.*}})
+// WEBASSEMBLY64: call i64 @llvm.wasm.atomic.wake(i8* %{{.*}}, i64 %{{.*}})
+}