diff --git a/Lib/rlcompleter.py b/Lib/rlcompleter.py
new file mode 100644
index 0000000000..bca4a7bc52
--- /dev/null
+++ b/Lib/rlcompleter.py
@@ -0,0 +1,205 @@
+"""Word completion for GNU readline.
+
+The completer completes keywords, built-ins and globals in a selectable
+namespace (which defaults to __main__); when completing NAME.NAME..., it
+evaluates (!) the expression up to the last dot and completes its attributes.
+
+It's very cool to do "import sys" type "sys.", hit the completion key (twice),
+and see the list of names defined by the sys module!
+
+Tip: to use the tab key as the completion key, call
+
+    readline.parse_and_bind("tab: complete")
+
+Notes:
+
+- Exceptions raised by the completer function are *ignored* (and generally cause
+  the completion to fail).  This is a feature -- since readline sets the tty
+  device in raw (or cbreak) mode, printing a traceback wouldn't work well
+  without some complicated hoopla to save, reset and restore the tty state.
+
+- The evaluation of the NAME.NAME... form may cause arbitrary application
+  defined code to be executed if an object with a __getattr__ hook is found.
+  Since it is the responsibility of the application (or the user) to enable this
+  feature, I consider this an acceptable risk.  More complicated expressions
+  (e.g. function calls or indexing operations) are *not* evaluated.
+
+- When the original stdin is not a tty device, GNU readline is never
+  used, and this module (and the readline module) are silently inactive.
+
+"""
+
+import atexit
+import builtins
+import __main__
+
+__all__ = ["Completer"]
+
+class Completer:
+    def __init__(self, namespace = None):
+        """Create a new completer for the command line.
+
+        Completer([namespace]) -> completer instance.
+
+        If unspecified, the default namespace where completions are performed
+        is __main__ (technically, __main__.__dict__). Namespaces should be
+        given as dictionaries.
+
+        Completer instances should be used as the completion mechanism of
+        readline via the set_completer() call:
+
+        readline.set_completer(Completer(my_namespace).complete)
+        """
+
+        if namespace and not isinstance(namespace, dict):
+            raise TypeError('namespace must be a dictionary')
+
+        # Don't bind to namespace quite yet, but flag whether the user wants a
+        # specific namespace or to use __main__.__dict__. This will allow us
+        # to bind to __main__.__dict__ at completion time, not now.
+        if namespace is None:
+            self.use_main_ns = 1
+        else:
+            self.use_main_ns = 0
+            self.namespace = namespace
+
+    def complete(self, text, state):
+        """Return the next possible completion for 'text'.
+
+        This is called successively with state == 0, 1, 2, ... until it
+        returns None.  The completion should begin with 'text'.
+
+        """
+        if self.use_main_ns:
+            self.namespace = __main__.__dict__
+
+        if not text.strip():
+            if state == 0:
+                if _readline_available:
+                    readline.insert_text('\t')
+                    readline.redisplay()
+                    return ''
+                else:
+                    return '\t'
+            else:
+                return None
+
+        if state == 0:
+            if "." in text:
+                self.matches = self.attr_matches(text)
+            else:
+                self.matches = self.global_matches(text)
+        try:
+            return self.matches[state]
+        except IndexError:
+            return None
+
+    def _callable_postfix(self, val, word):
+        if callable(val):
+            word = word + "("
+        return word
+
+    def global_matches(self, text):
+        """Compute matches when text is a simple name.
+
+        Return a list of all keywords, built-in functions and names currently
+        defined in self.namespace that match.
+
+        """
+        import keyword
+        matches = []
+        seen = {"__builtins__"}
+        n = len(text)
+        for word in keyword.kwlist:
+            if word[:n] == text:
+                seen.add(word)
+                if word in {'finally', 'try'}:
+                    word = word + ':'
+                elif word not in {'False', 'None', 'True',
+                                  'break', 'continue', 'pass',
+                                  'else'}:
+                    word = word + ' '
+                matches.append(word)
+        for nspace in [self.namespace, builtins.__dict__]:
+            for word, val in nspace.items():
+                if word[:n] == text and word not in seen:
+                    seen.add(word)
+                    matches.append(self._callable_postfix(val, word))
+        return matches
+
+    def attr_matches(self, text):
+        """Compute matches when text contains a dot.
+
+        Assuming the text is of the form NAME.NAME....[NAME], and is
+        evaluable in self.namespace, it will be evaluated and its attributes
+        (as revealed by dir()) are used as possible completions.  (For class
+        instances, class members are also considered.)
+
+        WARNING: this can still invoke arbitrary C code, if an object
+        with a __getattr__ hook is evaluated.
+
+        """
+        import re
+        m = re.match(r"(\w+(\.\w+)*)\.(\w*)", text)
+        if not m:
+            return []
+        expr, attr = m.group(1, 3)
+        try:
+            thisobject = eval(expr, self.namespace)
+        except Exception:
+            return []
+
+        # get the content of the object, except __builtins__
+        words = set(dir(thisobject))
+        words.discard("__builtins__")
+
+        if hasattr(thisobject, '__class__'):
+            words.add('__class__')
+            words.update(get_class_members(thisobject.__class__))
+        matches = []
+        n = len(attr)
+        if attr == '':
+            noprefix = '_'
+        elif attr == '_':
+            noprefix = '__'
+        else:
+            noprefix = None
+        while True:
+            for word in words:
+                if (word[:n] == attr and
+                    not (noprefix and word[:n+1] == noprefix)):
+                    match = "%s.%s" % (expr, word)
+                    try:
+                        val = getattr(thisobject, word)
+                    except Exception:
+                        pass  # Include even if attribute not set
+                    else:
+                        match = self._callable_postfix(val, match)
+                    matches.append(match)
+            if matches or not noprefix:
+                break
+            if noprefix == '_':
+                noprefix = '__'
+            else:
+                noprefix = None
+        matches.sort()
+        return matches
+
+def get_class_members(klass):
+    ret = dir(klass)
+    if hasattr(klass,'__bases__'):
+        for base in klass.__bases__:
+            ret = ret + get_class_members(base)
+    return ret
+
+try:
+    import readline
+except ImportError:
+    _readline_available = False
+else:
+    readline.set_completer(Completer().complete)
+    # Release references early at shutdown (the readline module's
+    # contents are quasi-immortal, and the completer function holds a
+    # reference to globals).
+    atexit.register(lambda: readline.set_completer(None))
+    _readline_available = True
diff --git a/Lib/test/test_rlcompleter.py b/Lib/test/test_rlcompleter.py
new file mode 100644
index 0000000000..9ea1a2c770
--- /dev/null
+++ b/Lib/test/test_rlcompleter.py
@@ -0,0 +1,143 @@
+import unittest
+from unittest.mock import patch
+import builtins
+import rlcompleter
+
+class CompleteMe:
+    """ Trivial class used in testing rlcompleter.Completer. """
+    spam = 1
+    _ham = 2
+
+
+class TestRlcompleter(unittest.TestCase):
+    def setUp(self):
+        self.stdcompleter = rlcompleter.Completer()
+        self.completer = rlcompleter.Completer(dict(spam=int,
+                                                    egg=str,
+                                                    CompleteMe=CompleteMe))
+
+        # forces stdcompleter to bind builtins namespace
+        self.stdcompleter.complete('', 0)
+
+    def test_namespace(self):
+        class A(dict):
+            pass
+        class B(list):
+            pass
+
+        self.assertTrue(self.stdcompleter.use_main_ns)
+        self.assertFalse(self.completer.use_main_ns)
+        self.assertFalse(rlcompleter.Completer(A()).use_main_ns)
+        self.assertRaises(TypeError, rlcompleter.Completer, B((1,)))
+
+    def test_global_matches(self):
+        # test with builtins namespace
+        self.assertEqual(sorted(self.stdcompleter.global_matches('di')),
+                         [x+'(' for x in dir(builtins) if x.startswith('di')])
+        self.assertEqual(sorted(self.stdcompleter.global_matches('st')),
+                         [x+'(' for x in dir(builtins) if x.startswith('st')])
+        self.assertEqual(self.stdcompleter.global_matches('akaksajadhak'), [])
+
+        # test with a customized namespace
+        self.assertEqual(self.completer.global_matches('CompleteM'),
+                         ['CompleteMe('])
+        self.assertEqual(self.completer.global_matches('eg'),
+                         ['egg('])
+        # XXX: see issue5256
+        self.assertEqual(self.completer.global_matches('CompleteM'),
+                         ['CompleteMe('])
+
+    def test_attr_matches(self):
+        # test with builtins namespace
+        self.assertEqual(self.stdcompleter.attr_matches('str.s'),
+                         ['str.{}('.format(x) for x in dir(str)
+                          if x.startswith('s')])
+        self.assertEqual(self.stdcompleter.attr_matches('tuple.foospamegg'), [])
+        expected = sorted({'None.%s%s' % (x, '(' if x != '__doc__' else '')
+                           for x in dir(None)})
+        self.assertEqual(self.stdcompleter.attr_matches('None.'), expected)
+        self.assertEqual(self.stdcompleter.attr_matches('None._'), expected)
+        self.assertEqual(self.stdcompleter.attr_matches('None.__'), expected)
+
+        # test with a customized namespace
+        self.assertEqual(self.completer.attr_matches('CompleteMe.sp'),
+                         ['CompleteMe.spam'])
+        self.assertEqual(self.completer.attr_matches('Completeme.egg'), [])
+        self.assertEqual(self.completer.attr_matches('CompleteMe.'),
+                         ['CompleteMe.mro(', 'CompleteMe.spam'])
+        self.assertEqual(self.completer.attr_matches('CompleteMe._'),
+                         ['CompleteMe._ham'])
+        matches = self.completer.attr_matches('CompleteMe.__')
+        for x in matches:
+            self.assertTrue(x.startswith('CompleteMe.__'), x)
+        self.assertIn('CompleteMe.__name__', matches)
+        self.assertIn('CompleteMe.__new__(', matches)
+
+        with patch.object(CompleteMe, "me", CompleteMe, create=True):
+            self.assertEqual(self.completer.attr_matches('CompleteMe.me.me.sp'),
+                             ['CompleteMe.me.me.spam'])
+            self.assertEqual(self.completer.attr_matches('egg.s'),
+                             ['egg.{}('.format(x) for x in dir(str)
+                              if x.startswith('s')])
+
+    def test_excessive_getattr(self):
+        # Ensure getattr() is invoked no more than once per attribute
+        class Foo:
+            calls = 0
+            @property
+            def bar(self):
+                self.calls += 1
+                return None
+        f = Foo()
+        completer = rlcompleter.Completer(dict(f=f))
+        self.assertEqual(completer.complete('f.b', 0), 'f.bar')
+        self.assertEqual(f.calls, 1)
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_uncreated_attr(self):
+        # Attributes like properties and slots should be completed even when
+        # they haven't been created on an instance
+        class Foo:
+            __slots__ = ("bar",)
+        completer = rlcompleter.Completer(dict(f=Foo()))
+        self.assertEqual(completer.complete('f.', 0), 'f.bar')
+
+    @unittest.mock.patch('rlcompleter._readline_available', False)
+    def test_complete(self):
+        completer = rlcompleter.Completer()
+        self.assertEqual(completer.complete('', 0), '\t')
+        self.assertEqual(completer.complete('a', 0), 'and ')
+        self.assertEqual(completer.complete('a', 1), 'as ')
+        self.assertEqual(completer.complete('as', 2), 'assert ')
+        self.assertEqual(completer.complete('an', 0), 'and ')
+        self.assertEqual(completer.complete('pa', 0), 'pass')
+        self.assertEqual(completer.complete('Fa', 0), 'False')
+        self.assertEqual(completer.complete('el', 0), 'elif ')
+        self.assertEqual(completer.complete('el', 1), 'else')
+        self.assertEqual(completer.complete('tr', 0), 'try:')
+
+    def test_duplicate_globals(self):
+        namespace = {
+            'False': None,  # Keyword vs builtin vs namespace
+            'assert': None,  # Keyword vs namespace
+            'try': lambda: None,  # Keyword vs callable
+            'memoryview': None,  # Callable builtin vs non-callable
+            'Ellipsis': lambda: None,  # Non-callable builtin vs callable
+        }
+        completer = rlcompleter.Completer(namespace)
+        self.assertEqual(completer.complete('False', 0), 'False')
+        self.assertIsNone(completer.complete('False', 1))  # No duplicates
+        # Space or colon added due to being a reserved keyword
+        self.assertEqual(completer.complete('assert', 0), 'assert ')
+        self.assertIsNone(completer.complete('assert', 1))
+        self.assertEqual(completer.complete('try', 0), 'try:')
+        self.assertIsNone(completer.complete('try', 1))
+        # No opening bracket "(" because we overrode the built-in class
+        self.assertEqual(completer.complete('memoryview', 0), 'memoryview')
+        self.assertIsNone(completer.complete('memoryview', 1))
+        self.assertEqual(completer.complete('Ellipsis', 0), 'Ellipsis(')
+        self.assertIsNone(completer.complete('Ellipsis', 1))
+
+if __name__ == '__main__':
+    unittest.main()