diff -r 703d9066c459 Python/ceval.c
--- a/Python/ceval.c	Mon Jun 20 21:42:05 2016 +0300
+++ b/Python/ceval.c	Mon Jun 20 23:18:28 2016 +0200
@@ -139,6 +139,7 @@ static int maybe_call_line_trace(Py_trac
                                  PyThreadState *, PyFrameObject *, int *, int *, int *);
 
 static PyObject * cmp_outcome(int, PyObject *, PyObject *);
+static PyObject * import_name(PyFrameObject *, PyObject *, PyObject *, PyObject *);
 static PyObject * import_from(PyObject *, PyObject *);
 static int import_all_from(PyObject *, PyObject *);
 static void format_exc_check_arg(PyObject *, const char *, PyObject *);
@@ -2803,45 +2804,15 @@ PyEval_EvalFrameEx(PyFrameObject *f, int
         }
 
         TARGET(IMPORT_NAME) {
-            _Py_IDENTIFIER(__import__);
             PyObject *name = GETITEM(names, oparg);
-            PyObject *func = _PyDict_GetItemId(f->f_builtins, &PyId___import__);
-            PyObject *from, *level, *args, *res;
-            if (func == NULL) {
-                PyErr_SetString(PyExc_ImportError,
-                                "__import__ not found");
-                goto error;
-            }
-            Py_INCREF(func);
-            from = POP();
-            level = TOP();
-            if (PyLong_AsLong(level) != -1 || PyErr_Occurred())
-                args = PyTuple_Pack(5,
-                            name,
-                            f->f_globals,
-                            f->f_locals == NULL ?
-                                  Py_None : f->f_locals,
-                            from,
-                            level);
-            else
-                args = PyTuple_Pack(4,
-                            name,
-                            f->f_globals,
-                            f->f_locals == NULL ?
-                                  Py_None : f->f_locals,
-                            from);
+            PyObject *fromlist = POP();
+            PyObject *level = TOP();
+            PyObject *res;
+            READ_TIMESTAMP(intr0);
+            res = import_name(f, name, fromlist, level);
             Py_DECREF(level);
-            Py_DECREF(from);
-            if (args == NULL) {
-                Py_DECREF(func);
-                STACKADJ(-1);
-                goto error;
-            }
-            READ_TIMESTAMP(intr0);
-            res = PyEval_CallObject(func, args);
+            Py_DECREF(fromlist);
             READ_TIMESTAMP(intr1);
-            Py_DECREF(args);
-            Py_DECREF(func);
             SET_TOP(res);
             if (res == NULL)
                 goto error;
@@ -5157,6 +5128,91 @@ cmp_outcome(int op, PyObject *v, PyObjec
 }
 
 static PyObject *
+import_name(PyFrameObject *f, PyObject *name, PyObject *fromlist, PyObject *level)
+{
+    _Py_IDENTIFIER(__import__);
+    static PyObject *orig_func = NULL;
+    PyObject *func = _PyDict_GetItemId(f->f_builtins, &PyId___import__);
+    PyObject *args, *res;
+    if (func == NULL) {
+        PyErr_SetString(PyExc_ImportError, "__import__ not found");
+        return NULL;
+    }
+    Py_INCREF(func);
+
+    /* Fast path for not overloaded __import__. */
+    if (orig_func == NULL) {
+        orig_func = _PyDict_GetItemId(
+                PyThreadState_GET()->interp->builtins_copy,
+                &PyId___import__);
+        if (orig_func == NULL) {
+            PyErr_Clear();
+        }
+    }
+    if (func == orig_func) {
+        int ilevel = 0;
+        Py_DECREF(func);
+        if (level != Py_None) {
+            ilevel = _PyLong_AsInt(level);
+            if (ilevel == -1 && PyErr_Occurred()) {
+                return NULL;
+            }
+        }
+        /* Fast path for simple import of the module which already is in
+           sys.modules. */
+        if (fromlist == Py_None && ilevel == 0 && PyUnicode_Check(name)) {
+            Py_ssize_t i = PyUnicode_FindChar(name, '.',
+                                0, PyUnicode_GET_LENGTH(name), 1);
+            if (i == -2) {
+                PyErr_Clear();
+            }
+            else if (i == -1) {
+                res = PyDict_GetItem(PyImport_GetModuleDict(), name);
+                if (res == NULL) {
+                    PyErr_Clear();
+                }
+                else if (res != Py_None) {
+                    Py_INCREF(res);
+                    return res;
+                }
+            }
+        }
+
+        res = PyImport_ImportModuleLevelObject(
+                    name,
+                    f->f_globals,
+                    f->f_locals == NULL ? Py_None : f->f_locals,
+                    fromlist,
+                    ilevel);
+        return res;
+    }
+
+    if (level != Py_None) {
+        args = PyTuple_Pack(5,
+                    name,
+                    f->f_globals,
+                    f->f_locals == NULL ? Py_None : f->f_locals,
+                    fromlist,
+                    level);
+    }
+    else {
+        args = PyTuple_Pack(4,
+                    name,
+                    f->f_globals,
+                    f->f_locals == NULL ? Py_None : f->f_locals,
+                    fromlist);
+    }
+    if (args == NULL) {
+        Py_DECREF(func);
+        return NULL;
+    }
+    res = PyEval_CallObject(func, args);
+    Py_DECREF(args);
+    Py_DECREF(func);
+    return res;
+}
+
+static PyObject *
 import_from(PyObject *v, PyObject *name)
 {
     PyObject *x;