diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -685,6 +685,8 @@
   (`#64005 <https://github.com/llvm/llvm-project/issues/64005>_`)
 - Fix crash on nested templated class with template function call.
   (`#61159 <https://github.com/llvm/llvm-project/issues/61159>_`)
+- Fix crash on use of a variadic overloaded operator.
+  (`#42535 <https://github.com/llvm/llvm-project/issues/42535>_`)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -13997,6 +13997,10 @@
         std::swap(Args[0], Args[1]);
 
       if (FnDecl) {
+
+        if (FnDecl->isInvalidDecl())
+          return ExprError();
+
         Expr *Base = nullptr;
         // We matched an overloaded operator. Build a call to that
         // operator.
diff --git a/clang/test/SemaCXX/overloaded-operator-decl.cpp b/clang/test/SemaCXX/overloaded-operator-decl.cpp
--- a/clang/test/SemaCXX/overloaded-operator-decl.cpp
+++ b/clang/test/SemaCXX/overloaded-operator-decl.cpp
@@ -58,3 +58,9 @@
     A()(i);
   }
 }
+
+namespace GH42535 {
+class E {};
+void operator+(E, ...) {} // expected-error{{overloaded 'operator+' cannot be variadic}}
+void d() { E() + E(); }
+}