diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -737,6 +737,22 @@
                "   function a() {\n"
                "  return   1;\n"
                "}  \n");
+  // clang-format must not insert breaks between async and function, otherwise
+  // automatic semicolon insertion may trigger (in particular in a class body).
+  verifyFormat("async function\n"
+               "hello(\n"
+               "    myparamnameiswaytooloooong) {\n"
+               "}",
+               "async function hello(myparamnameiswaytooloooong) {}",
+               getGoogleJSStyleWithColumns(10));
+  verifyFormat("class C {\n"
+               "  async hello(\n"
+               "      myparamnameiswaytooloooong) {\n"
+               "  }\n"
+               "}",
+               "class C {\n"
+               "  async hello(myparamnameiswaytooloooong) {} }",
+               getGoogleJSStyleWithColumns(10));
   verifyFormat("async function* f() {\n"
                "  yield fetch(x);\n"
                "}");