diff -r 0d77a17567a4 Modules/socketmodule.c
--- a/Modules/socketmodule.c	Mon Mar 07 14:52:46 2016 -0500
+++ b/Modules/socketmodule.c	Thu Mar 10 19:06:01 2016 -0800
@@ -4034,6 +4034,15 @@
             return set_error();
         }
         return PyLong_FromUnsignedLong(recv); }
+    case SIO_LOOPBACK_FAST_PATH: {
+        unsigned int option;
+        if (!PyArg_ParseTuple(arg, "kI:ioctl", &cmd, &option))
+            return NULL;
+        if (WSAIoctl(s->sock_fd, cmd, &option, sizeof(option),
+                         NULL, 0, &recv, NULL, NULL) == SOCKET_ERROR) {
+            return set_error();
+        }
+        return PyLong_FromUnsignedLong(recv); }
     default:
         PyErr_Format(PyExc_ValueError, "invalid ioctl command %d", cmd);
         return NULL;
@@ -4044,7 +4053,8 @@
 \n\
 Control the socket with WSAIoctl syscall. Currently supported 'cmd' values are\n\
 SIO_RCVALL:  'option' must be one of the socket.RCVALL_* constants.\n\
-SIO_KEEPALIVE_VALS:  'option' is a tuple of (onoff, timeout, interval).");
+SIO_KEEPALIVE_VALS:  'option' is a tuple of (onoff, timeout, interval).\n\
+SIO_LOOPBACK_FAST_PATH: 'option' is a boolean value (on or off)");
 #endif
 
 #if defined(MS_WINDOWS)
@@ -7220,8 +7230,8 @@
 
 #ifdef SIO_RCVALL
     {
-        DWORD codes[] = {SIO_RCVALL, SIO_KEEPALIVE_VALS};
-        const char *names[] = {"SIO_RCVALL", "SIO_KEEPALIVE_VALS"};
+        DWORD codes[] = {SIO_RCVALL, SIO_KEEPALIVE_VALS, SIO_LOOPBACK_FAST_PATH};
+        const char *names[] = {"SIO_RCVALL", "SIO_KEEPALIVE_VALS", "SIO_LOOPBACK_FAST_PATH"};
         int i;
         for(i = 0; i<Py_ARRAY_LENGTH(codes); ++i) {
             PyObject *tmp;