Index: lib2to3/tests/test_fixers.py
===================================================================
--- lib2to3/tests/test_fixers.py	(revision 67657)
+++ lib2to3/tests/test_fixers.py	(working copy)
@@ -3227,6 +3227,52 @@
             """
         self.unchanged(s)
 
+class Test_exitfunc(FixerTestCase):
+
+    fixer = "exitfunc"
+
+    def test_1(self):
+        b = """
+            import sys
+            sys.exitfunc = my_atexit
+            """
+        a = """
+            import sys
+            import atexit
+            atexit.register(my_atexit)
+            """
+        self.check(b, a)
+
+    def test_2(self):
+        b = """
+            import sys
+            sys.exitfunc = do(d)/a()+complex(f=23, g=23)*expression
+            """
+        a = """
+            import sys
+            import atexit
+            atexit.register(do(d)/a()+complex(f=23, g=23)*expression)
+            """
+        self.check(b, a)
+
+    def test_3(self):
+        b = """
+            import sys
+            def f():
+                sys.exitfunc = func
+            """
+        a = """
+            import sys
+            import atexit
+            def f():
+                atexit.register(func)
+           """
+        self.check(b, a)
+
+    def test_unchanged(self):
+        s = """f(sys.exitfunc)"""
+        self.unchanged(s)
+
 class Test_basestring(FixerTestCase):
     fixer = "basestring"
 
Index: lib2to3/fixes/fix_exitfunc.py
===================================================================
--- lib2to3/fixes/fix_exitfunc.py	(revision 0)
+++ lib2to3/fixes/fix_exitfunc.py	(revision 0)
@@ -0,0 +1,29 @@
+"""Fixed that Convers use of sys.exitfunc to use the atexit module.
+"""
+# Author: Armin Ronacher, Benjamin Peterson
+
+# Local imports
+from .. import pytree, fixer_base
+from ..fixer_util import Name, Attr, Call, does_tree_import, touch_import
+
+
+class FixExitfunc(fixer_base.BaseFix):
+
+    PATTERN = """
+        expr_stmt<
+            power< 'sys' trailer< '.' 'exitfunc' > >
+        '=' func=any >
+    """
+
+    def transform(self, node, results):
+        # do nothing if sys is not imported
+        if not does_tree_import(None, "sys", node):
+            return
+
+        touch_import(None, "atexit", node)
+
+        func = results["func"].clone()
+        func.set_prefix("")
+        register = pytree.Node(self.syms.power,
+                               Attr(Name("atexit"), Name("register")))
+        node.replace(Call(register, [func], node.get_prefix()))