diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 7a5771921b..a1d5abff9d 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -4425,6 +4425,29 @@ test_pythread_tss_key_state(PyObject *self, PyObject *args)
 }
 
 
+static PyObject *
+bench_warn(PyObject *self, PyObject *args)
+{
+    _PyTime_t t0, dt;
+    Py_ssize_t loops;
+    double d;
+
+    if (!PyArg_ParseTuple(args, "n", &loops)) {
+        return NULL;
+    }
+
+    t0 = _PyTime_GetPerfCounter();
+    for (Py_ssize_t i=0; i<loops; i++) {
+        if (PyErr_WarnEx(PyExc_Warning, "test", 1) < 0) {
+            return NULL;
+        }
+    }
+    dt = _PyTime_GetPerfCounter() - t0;
+    d = _PyTime_AsSecondsDouble(dt);
+    return PyFloat_FromDouble(d);
+}
+
+
 static PyMethodDef TestMethods[] = {
     {"raise_exception",         raise_exception,                 METH_VARARGS},
     {"raise_memoryerror",   (PyCFunction)raise_memoryerror,  METH_NOARGS},
@@ -4641,6 +4664,7 @@ static PyMethodDef TestMethods[] = {
     {"get_mapping_values", get_mapping_values, METH_O},
     {"get_mapping_items", get_mapping_items, METH_O},
     {"test_pythread_tss_key_state", test_pythread_tss_key_state, METH_VARARGS},
+    {"bench", bench_warn, METH_VARARGS},
     {NULL, NULL} /* sentinel */
 };