diff -r 5e25fff9f2ba Objects/dictobject.c
--- a/Objects/dictobject.c	Wed Jan 18 18:06:32 2017 +0100
+++ b/Objects/dictobject.c	Wed Jan 18 18:07:13 2017 +0100
@@ -2322,13 +2322,13 @@ dict_fromkeys_impl(PyTypeObject *type, P
 }
 
 static int
-dict_update_common(PyObject *self, PyObject *args, PyObject *kwds,
-                   const char *methname)
+dict_update_common(PyObject *self, PyObject **args, Py_ssize_t nargs,
+                   PyObject *kwds, const char *methname)
 {
     PyObject *arg = NULL;
     int result = 0;
 
-    if (!PyArg_UnpackTuple(args, methname, 0, 1, &arg))
+    if (!_PyArg_UnpackStack(args, nargs, methname, 0, 1, &arg))
         result = -1;
 
     else if (arg != NULL) {
@@ -2348,9 +2348,38 @@ dict_update_common(PyObject *self, PyObj
 }
 
 static PyObject *
-dict_update(PyObject *self, PyObject *args, PyObject *kwds)
+dict_update(PyObject *self, PyObject **args, Py_ssize_t nargs,
+            PyObject *kwnames)
 {
-    if (dict_update_common(self, args, kwds, "update") != -1)
+    PyObject *kwargs;
+
+    if (kwnames != NULL) {
+        PyObject **values;
+        Py_ssize_t nkwargs;
+        Py_ssize_t i;
+
+        nkwargs = PyTuple_GET_SIZE(kwnames);
+        kwargs = _PyDict_NewPresized(nkwargs);
+        if (kwargs == NULL) {
+            return NULL;
+        }
+
+        values = args + nargs;
+        for (i = 0; i < nkwargs; i++) {
+            PyObject *key = PyTuple_GET_ITEM(kwnames, i);
+            PyObject *value = *values++;
+            assert(PyDict_GetItem(kwargs, key) == NULL);
+            if (PyDict_SetItem(kwargs, key, value)) {
+                Py_DECREF(kwargs);
+                return NULL;
+            }
+        }
+    }
+    else {
+        kwargs = NULL;
+    }
+
+    if (dict_update_common(self, args, nargs, kwargs, "update") != -1)
         Py_RETURN_NONE;
     return NULL;
 }
@@ -3130,7 +3159,7 @@ static PyMethodDef mapp_methods[] = {
     items__doc__},
     {"values",          (PyCFunction)dictvalues_new,    METH_NOARGS,
     values__doc__},
-    {"update",          (PyCFunction)dict_update,       METH_VARARGS | METH_KEYWORDS,
+    {"update",          (PyCFunction)dict_update,       METH_FASTCALL,
      update__doc__},
     DICT_FROMKEYS_METHODDEF
     {"clear",           (PyCFunction)dict_clear,        METH_NOARGS,
@@ -3219,7 +3248,10 @@ dict_new(PyTypeObject *type, PyObject *a
 static int
 dict_init(PyObject *self, PyObject *args, PyObject *kwds)
 {
-    return dict_update_common(self, args, kwds, "dict");
+    return dict_update_common(self,
+                              &PyTuple_GET_ITEM(args, 0),
+                              PyTuple_GET_SIZE(args),
+                              kwds, "dict");
 }
 
 static PyObject *