diff -r 6c2e2de5ab8e Lib/test/test_threading.py
--- a/Lib/test/test_threading.py	Sat Jul 30 23:51:13 2016 -0700
+++ b/Lib/test/test_threading.py	Tue Aug 02 12:45:33 2016 +0800
@@ -1043,6 +1043,20 @@
         self.assertEqual(out, b'')
         self.assertNotIn("Unhandled exception", err.decode())
 
+    def test_bare_raise_in_brand_new_thread(self):
+        # issue 27558
+        script = r"""if True:
+        import threading
+        def foo():
+            raise
+        threading.Thread(target=foo).start()
+        """
+        rc, out, err = assert_python_ok("-c", script)
+        err = err.decode()
+        self.assertIn('reraise', err)
+        self.assertIn('RuntimeError', err)
+        self.assertNotIn('SystemError', err)
+
 
 class TimerTests(BaseTestCase):
 
diff -r 6c2e2de5ab8e Python/ceval.c
--- a/Python/ceval.c	Sat Jul 30 23:51:13 2016 -0700
+++ b/Python/ceval.c	Tue Aug 02 12:45:33 2016 +0800
@@ -4141,7 +4141,7 @@
         type = tstate->exc_type;
         value = tstate->exc_value;
         tb = tstate->exc_traceback;
-        if (type == Py_None) {
+        if (type == Py_None || type == NULL) {
             PyErr_SetString(PyExc_RuntimeError,
                             "No active exception to reraise");
             return 0;