diff --git a/py/builtin/builtin31.py b/py/builtin/builtin31.py
index 47283462e..015ddb6c1 100644
--- a/py/builtin/builtin31.py
+++ b/py/builtin/builtin31.py
@@ -11,9 +11,25 @@ if sys.version_info >= (3, 0):
             obj = obj.encode(encoding)
         return str(obj, encoding)
 
+    def execfile(fn, globs=None, locs=None):
+        if globs is None:
+            back = sys._getframe(1)
+            globs = back.f_globals
+            locs = back.f_locals
+            del back
+        elif locs is None:
+            locs = globs
+        fp = open(fn, "rb")
+        try:
+            source = fp.read()
+        finally:
+            fp.close()
+        exec_(source, globs, locs)
+
 else:
     _totext = unicode 
     _basestring = basestring
+    execfile = execfile
 
     import __builtin__ as builtins
     def print_(*args, **kwargs):
diff --git a/py/builtin/testing/test_builtin.py b/py/builtin/testing/test_builtin.py
index 43df15f5e..05454792e 100644
--- a/py/builtin/testing/test_builtin.py
+++ b/py/builtin/testing/test_builtin.py
@@ -84,6 +84,18 @@ def test_print_simple():
     s = f.getvalue()
     assert s == "xyzabc"
 
+def test_execfile(tmpdir):
+    test_file = tmpdir.join("test.py")
+    test_file.write("x = y")
+    ns = {"y" : 42}
+    py.builtin.execfile(str(test_file), ns)
+    assert ns["x"] == 42
+    class A:
+        y = 3
+        x = 4
+        py.builtin.execfile(str(test_file))
+    assert A.x == 3
+
 def test_totext():
     py.builtin._totext("hello", "UTF-8")