Index: Include/pyport.h
===================================================================
--- Include/pyport.h	(revision 84189)
+++ Include/pyport.h	(working copy)
@@ -832,4 +832,13 @@
 #endif
 #endif
 
+/*
+ * System-dependent ways of injecting a breakpoint:
+ */
+#if defined(MS_WINDOWS) && defined(_DEBUG)
+#  define Py_BREAKPOINT()  DebugBreak()
+#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64))
+#  define Py_BREAKPOINT()  __asm__ __volatile__ ("int $03")
+#endif
+
 #endif /* Py_PYPORT_H */
Index: Python/sysmodule.c
===================================================================
--- Python/sysmodule.c	(revision 84189)
+++ Python/sysmodule.c	(working copy)
@@ -67,7 +67,23 @@
         return PyDict_SetItemString(sd, name, v);
 }
 
+#ifdef Py_BREAKPOINT
+PyDoc_STRVAR(breakpoint_doc,
+"breakpoint() -> None\n"
+"\n"
+"Inject a breakpoint signal in this process, for use when running CPython\n"
+"under a debugger.\n"
+);
+
 static PyObject *
+sys_breakpoint(PyObject *self, PyObject *noargs)
+{
+    Py_BREAKPOINT();
+    Py_RETURN_NONE;
+}
+#endif /* Py_BREAKPOINT */
+
+static PyObject *
 sys_displayhook(PyObject *self, PyObject *o)
 {
     PyObject *outf;
@@ -986,6 +1002,9 @@
 
 static PyMethodDef sys_methods[] = {
     /* Might as well keep this in alphabetic order */
+#ifdef Py_BREAKPOINT
+    {"breakpoint", sys_breakpoint, METH_NOARGS, breakpoint_doc},
+#endif
     {"callstats", (PyCFunction)PyEval_GetCallStats, METH_NOARGS,
      callstats_doc},
     {"_clear_type_cache",       sys_clear_type_cache,     METH_NOARGS,