diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 223e93e7c3d1..ae299c3c98e8 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -4752,8 +4752,12 @@ Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
                                      VK_RValue, RParenLoc);
 
   // Bail out early if calling a builtin with custom typechecking.
-  if (BuiltinID && Context.BuiltinInfo.hasCustomTypechecking(BuiltinID))
-    return CheckBuiltinFunctionCall(FDecl, BuiltinID, TheCall);
+  if (BuiltinID && Context.BuiltinInfo.hasCustomTypechecking(BuiltinID)) {
+    ExprResult Res = CorrectDelayedTyposInExpr(TheCall);
+    if (!Res.isUsable() || !isa<CallExpr>(Res.get()))
+      return Res;
+    return CheckBuiltinFunctionCall(FDecl, BuiltinID, cast<CallExpr>(Res.get()));
+  }
 
  retry:
   const FunctionType *FuncT;
diff --git a/clang/test/SemaCXX/typo-correction-delayed.cpp b/clang/test/SemaCXX/typo-correction-delayed.cpp
index 124f0ec2a1ca..bff1d7633fc6 100644
--- a/clang/test/SemaCXX/typo-correction-delayed.cpp
+++ b/clang/test/SemaCXX/typo-correction-delayed.cpp
@@ -93,3 +93,12 @@ void f(NestedNode *node) {
   NestedNode *next = node->Next();  // expected-error-re {{no member named 'Next' in 'initializerCorrections::NestedNode'{{$}}}}
 }
 }
+
+namespace PR21669 {
+void f(int *i) {
+  // Check that arguments to a builtin with custom type checking are corrected
+  // properly, since calls to such builtins bypass much of the normal code path
+  // for building and checking the call.
+  __atomic_load(i, i, something_something);  // expected-error-re {{use of undeclared identifier 'something_something'{{$}}}}
+}
+}