Index: include/clang/Basic/Builtins.def
===================================================================
--- include/clang/Basic/Builtins.def
+++ include/clang/Basic/Builtins.def
@@ -1443,6 +1443,7 @@
 BUILTIN(__builtin_coro_done, "bv*", "n")
 BUILTIN(__builtin_coro_promise, "v*v*IiIb", "n")
 
+BUILTIN(__builtin_coro_size_chk, "vz", "n")
 BUILTIN(__builtin_coro_size, "z", "n")
 BUILTIN(__builtin_coro_frame, "v*", "n")
 BUILTIN(__builtin_coro_noop, "v*", "n")
Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp
+++ lib/CodeGen/CGBuiltin.cpp
@@ -3276,12 +3276,19 @@
     return RValue::get(EmitMSVCBuiltinExpr(MSVCIntrin::__fastfail, E));
 
   case Builtin::BI__builtin_coro_size: {
-    auto & Context = getContext();
+    auto &Context = getContext();
     auto SizeTy = Context.getSizeType();
     auto T = Builder.getIntNTy(Context.getTypeSize(SizeTy));
     Value *F = CGM.getIntrinsic(Intrinsic::coro_size, T);
     return RValue::get(Builder.CreateCall(F));
   }
+  case Builtin::BI__builtin_coro_size_chk: {
+    auto &Context = getContext();
+    auto SizeTy = Context.getSizeType();
+    auto T = Builder.getIntNTy(Context.getTypeSize(SizeTy));
+    Value *F = CGM.getIntrinsic(Intrinsic::coro_size_chk, T);
+    return RValue::get(Builder.CreateCall(F, EmitScalarExpr(E->getArg(0))));
+  }
 
   case Builtin::BI__builtin_coro_id:
     return EmitCoroutineIntrinsic(E, Intrinsic::coro_id);