Index: Objects/object.c
===================================================================
--- Objects/object.c	(revision 58125)
+++ Objects/object.c	(working copy)
@@ -404,7 +404,12 @@
 	if (Py_Type(v)->tp_str == NULL)
 		return PyObject_Repr(v);
 
+	/* It is possible for a type to have a tp_str representation that loops
+	   infinitely. */
+	if (Py_EnterRecursiveCall(" while getting the str of an object"))
+		return NULL;
 	res = (*Py_Type(v)->tp_str)(v);
+	Py_LeaveRecursiveCall();
 	if (res == NULL)
 		return NULL;
 	type_ok = PyString_Check(res);
Index: Objects/tupleobject.c
===================================================================
--- Objects/tupleobject.c	(revision 58125)
+++ Objects/tupleobject.c	(working copy)
@@ -208,6 +208,15 @@
 	PyObject *s, *temp;
 	PyObject *pieces, *result = NULL;
 
+	/* While not mutable, it is still possible to end up with a cycle in a
+	   tuple through an object that stores itself within a tuple (and thus
+	   infinitely asks for the repr of itself). This should only be
+	   possible within a type. */
+	i = Py_ReprEnter((PyObject *)v);
+	if (i != 0) {
+		return i > 0 ? PyString_FromString("(...)") : NULL;
+	}
+
 	n = Py_Size(v);
 	if (n == 0)
 		return PyString_FromString("()");
@@ -218,7 +227,10 @@
 
 	/* Do repr() on each element. */
 	for (i = 0; i < n; ++i) {
+		if (Py_EnterRecursiveCall(" while getting the repr of a tuple"))
+			goto Done;
 		s = PyObject_Repr(v->ob_item[i]);
+		Py_LeaveRecursiveCall();
 		if (s == NULL)
 			goto Done;
 		PyTuple_SET_ITEM(pieces, i, s);
@@ -253,6 +265,7 @@
 
 Done:
 	Py_DECREF(pieces);
+	Py_ReprLeave((PyObject *)v);
 	return result;
 }