diff --git a/thirdpart/urlobject/__init__.py b/thirdpart/urlobject/__init__.py
new file mode 100644
index 0000000000..2f71db6f5d
--- /dev/null
+++ b/thirdpart/urlobject/__init__.py
@@ -0,0 +1 @@
+from urlobject import URLObject
diff --git a/thirdpart/urlobject/netloc.py b/thirdpart/urlobject/netloc.py
new file mode 100644
index 0000000000..9c0bc90bb8
--- /dev/null
+++ b/thirdpart/urlobject/netloc.py
@@ -0,0 +1,113 @@
+import urlparse
+
+
+class Netloc(unicode):
+
+    """
+    A netloc string (``username:password@hostname:port``).
+
+    Contains methods for accessing and (non-destructively) modifying those four
+    components of the netloc. All methods return new instances.
+    """
+
+    def __repr__(self):
+        return 'Netloc(%r)' % (unicode(self),)
+
+    @classmethod
+    def __unsplit(cls, username, password, hostname, port):
+        """Put together a :class:`Netloc` from its constituent parts."""
+        auth_string = u''
+        if username:
+            auth_string = username
+            if password:
+                auth_string += u':' + password
+            auth_string += '@'
+        port_string = u''
+        if port is not None:
+            port_string = u':%d' % port
+        return cls(auth_string + hostname + port_string)
+
+    @property
+    def username(self):
+        """The username portion of this netloc, or ``None``."""
+        return self.__urlsplit.username
+
+    def with_username(self, username):
+        """Replace or add a username to this netloc."""
+        return self.__replace(username=username)
+
+    def without_username(self):
+        """Remove any username (and password) from this netloc."""
+        return self.without_password().with_username('')
+
+    @property
+    def password(self):
+        """The password portion of this netloc, or ``None``."""
+        return self.__urlsplit.password
+
+    def with_password(self, password):
+
+        """
+        Replace or add a password to this netloc.
+
+        Raises a ``ValueError`` if you attempt to add a password to a netloc
+        with no username.
+        """
+
+        if password and not self.username:
+            raise ValueError("Can't set a password on a netloc with no username")
+        return self.__replace(password=password)
+
+    def without_password(self):
+        """Remove any password from this netloc."""
+        return self.with_password('')
+
+    @property
+    def auth(self):
+        """The username and password of this netloc as a 2-tuple."""
+        return (self.username, self.password)
+
+    def with_auth(self, username, *password):
+        """Replace or add a username and password in one method call."""
+        netloc = self.without_auth()
+        if password:
+            return netloc.with_username(username).with_password(*password)
+        return netloc.with_username(username)
+
+    def without_auth(self):
+        return self.without_password().without_username()
+
+    @property
+    def hostname(self):
+        """The hostname portion of this netloc."""
+        return self.__urlsplit.hostname
+
+    def with_hostname(self, hostname):
+        """Replace the hostname on this netloc."""
+        return self.__replace(hostname=hostname)
+
+    @property
+    def port(self):
+        """The port number on this netloc (as an ``int``), or ``None``."""
+        return self.__urlsplit.port
+
+    def with_port(self, port):
+        """Replace or add a port number to this netloc."""
+        return self.__replace(port=port)
+
+    def without_port(self):
+        """Remove any port number from this netloc."""
+        return self.__replace(port=None)
+
+    @property
+    def __urlsplit(self):
+        return urlparse.SplitResult('', self, '', '', '')
+
+    def __replace(self, **params):
+        """Replace any number of components on this netloc."""
+        unsplit_args = {'username': self.username,
+                        'password': self.password,
+                        'hostname': self.hostname,
+                        'port': self.port}
+        unsplit_args.update(params)
+        return self.__unsplit(**unsplit_args)
diff --git a/thirdpart/urlobject/path.py b/thirdpart/urlobject/path.py
new file mode 100644
index 0000000000..1123df4e69
--- /dev/null
+++ b/thirdpart/urlobject/path.py
@@ -0,0 +1,145 @@
+# -*- coding: utf-8 -*-
+
+import posixpath
+import urllib
+import urlparse
+
+
+class Root(object):
+
+    """A descriptor which always returns the root path."""
+
+    def __get__(self, instance, cls):
+        return cls('/')
+
+
+class URLPath(unicode):
+
+    root = Root()
+
+    def __repr__(self):
+        return 'URLPath(%r)' % (unicode(self),)
+
+    @classmethod
+    def join_segments(cls, segments, absolute=True):
+        """Create a :class:`URLPath` from an iterable of segments."""
+        path = cls('/')
+        for segment in segments:
+            path = path.add_segment(segment)
+        return path
+
+    @property
+    def segments(self):
+        """
+        Split this path into (decoded) segments.
+
+            >>> URLPath(u'/a/b/c').segments
+            (u'a', u'b', u'c')
+
+        Non-leaf nodes will have a trailing empty string, and percent encodes
+        will be decoded:
+
+            >>> URLPath(u'/a%20b/c%20d/').segments
+            (u'a b', u'c d', u'')
+        """
+        segments = tuple(map(path_decode, self.split('/')))
+        if segments[0] == u'':
+            return segments[1:]
+        return segments
+
+    @property
+    def parent(self):
+        """
+        The parent of this node.
+
+            >>> URLPath(u'/a/b/c').parent
+            URLPath(u'/a/b/')
+            >>> URLPath(u'/foo/bar/').parent
+            URLPath(u'/foo/')
+        """
+        if self.is_leaf:
+            return self.relative('.')
+        return self.relative('..')
+
+    @property
+    def is_leaf(self):
+        """
+        Is this path a leaf node?
+
+            >>> URLPath(u'/a/b/c').is_leaf
+            True
+            >>> URLPath(u'/a/b/').is_leaf
+            False
+        """
+        return self and self.segments[-1] != u''
+
+    @property
+    def is_relative(self):
+        """
+        Is this path relative?
+
+            >>> URLPath(u'a/b/c').is_relative
+            True
+            >>> URLPath(u'/a/b/c').is_relative
+            False
+        """
+        return self[0] != u'/'
+
+    @property
+    def is_absolute(self):
+        """
+        Is this path absolute?
+
+            >>> URLPath(u'a/b/c').is_absolute
+            False
+            >>> URLPath(u'/a/b/c').is_absolute
+            True
+        """
+        return self[0] == u'/'
+
+    def relative(self, rel_path):
+        """
+        Resolve a relative path against this one.
+
+            >>> URLPath(u'/a/b/c').relative('.')
+            URLPath(u'/a/b/')
+            >>> URLPath(u'/a/b/c').relative('d')
+            URLPath(u'/a/b/d')
+            >>> URLPath(u'/a/b/c').relative('../d')
+            URLPath(u'/a/d')
+        """
+        return type(self)(urlparse.urljoin(self, rel_path))
+
+    def add_segment(self, segment):
+        u"""
+        Add a segment to this path.
+
+            >>> URLPath(u'/a/b/').add_segment('c')
+            URLPath(u'/a/b/c')
+
+        Non-ASCII and reserved characters (including slashes) will be encoded:
+
+            >>> URLPath(u'/a/b/').add_segment(u'dé/f')
+            URLPath(u'/a/b/d%C3%A9%2Ff')
+        """
+        return type(self)(posixpath.join(self, path_encode(segment)))
+
+    def add(self, path):
+        u"""
+        Add a partial path to this one.
+
+        The only difference between this and :meth:`add_segment` is that slash
+        characters will not be encoded, making it suitable for adding more than
+        one path segment at a time:
+
+            >>> URLPath(u'/a/b/').add(u'dé/f/g')
+            URLPath(u'/a/b/d%C3%A9/f/g')
+        """
+        return type(self)(posixpath.join(self, path_encode(path, safe='/')))
+
+
+def path_encode(string, safe=''):
+    return urllib.quote(string.encode('utf-8'), safe=safe)
+
+def path_decode(string):
+    return urllib.unquote(string).decode('utf-8')
diff --git a/thirdpart/urlobject/ports.py b/thirdpart/urlobject/ports.py
new file mode 100644
index 0000000000..27b8ef3400
--- /dev/null
+++ b/thirdpart/urlobject/ports.py
@@ -0,0 +1,25 @@
+"""Default port numbers for the URI schemes supported by urlparse."""
+
+DEFAULT_PORTS = {
+    'ftp': 21,
+    'gopher': 70,
+    'hdl': 2641,
+    'http': 80,
+    'https': 443,
+    'imap': 143,
+    'mms': 651,
+    'news': 2009,
+    'nntp': 119,
+    'prospero': 191,
+    'rsync': 873,
+    'rtsp': 554,
+    'rtspu': 554,
+    'sftp': 115,
+    'shttp': 80,
+    'sip': 5060,
+    'sips': 5061,
+    'snews': 2009,
+    'svn': 3690,
+    'svn+ssh': 22,
+    'telnet': 23,
+}
diff --git a/thirdpart/urlobject/query_string.py b/thirdpart/urlobject/query_string.py
new file mode 100644
index 0000000000..4ca203a6af
--- /dev/null
+++ b/thirdpart/urlobject/query_string.py
@@ -0,0 +1,109 @@
+import collections
+import re
+import urllib
+import urlparse
+
+
+class QueryString(unicode):
+
+    def __repr__(self):
+        return 'QueryString(%r)' % (unicode(self),)
+
+    @property
+    def list(self):
+        result = []
+        if not self:
+            # Empty string => empty list.
+            return result
+
+        name_value_pairs = re.split(r'[\&\;]', self)
+        for name_value_pair in name_value_pairs:
+            # Split the pair string into a naive, encoded (name, value) pair.
+            name_value = name_value_pair.split('=', 1)
+            # 'param=' => ('param', None)
+            if len(name_value) == 1:
+                name, value = name_value + [None]
+            # 'param=value' => ('param', 'value')
+            # 'param=' => ('param', '')
+            else:
+                name, value = name_value
+
+            name = qs_decode(name)
+            if value is not None:
+                value = qs_decode(value)
+
+            result.append((name, value))
+        return result
+
+    @property
+    def dict(self):
+        return dict(self.list)
+
+    @property
+    def multi_dict(self):
+        result = collections.defaultdict(list)
+        for name, value in self.list:
+            result[name].append(value)
+        return dict(result)
+
+    def add_param(self, name, value):
+        if value is None:
+            parameter = qs_encode(name)
+        else:
+            parameter = qs_encode(name) + '=' + qs_encode(value)
+        if self:
+            return type(self)(self + '&' + parameter)
+        return type(self)(parameter)
+
+    def add_params(self, *args, **kwargs):
+        params_list = get_params_list(*args, **kwargs)
+        new = self
+        for name, value in params_list:
+            new = new.add_param(name, value)
+        return new
+
+    def del_param(self, name):
+        params = [(n, v) for n, v in self.list if n != name]
+        qs = type(self)('')
+        for param in params:
+            qs = qs.add_param(*param)
+        return qs
+
+    def set_param(self, name, value):
+        return self.del_param(name).add_param(name, value)
+
+    def set_params(self, *args, **kwargs):
+        params_list = get_params_list(*args, **kwargs)
+        new = self
+        for name, value in params_list:
+            new = new.set_param(name, value)
+        return new
+
+    def del_params(self, params):
+        deleted = set(params)
+        params = [(name, value) for name, value in self.list
+                  if name not in deleted]
+        qs = type(self)('')
+        for param in params:
+            qs = qs.add_param(*param)
+        return qs
+
+
+qs_encode = lambda s: urllib.quote(s.encode('utf-8'))
+qs_decode = lambda s: urllib.unquote(str(s).replace('+', ' ')).decode('utf-8')
+
+
+def get_params_list(*args, **kwargs):
+    """Turn dict-like arguments into an ordered list of pairs."""
+    params = []
+    if args:
+        if len(args) > 1:
+            raise TypeError("Expected at most 1 arguments, got 2")
+        arg = args[0]
+        if hasattr(arg, 'items'):
+            params.extend(arg.items())
+        else:
+            params.extend(list(arg))
+    if kwargs:
+        params.extend(kwargs.items())
+    return params
diff --git a/thirdpart/urlobject/urlobject.py b/thirdpart/urlobject/urlobject.py
new file mode 100644
index 0000000000..d788f2f71e
--- /dev/null
+++ b/thirdpart/urlobject/urlobject.py
@@ -0,0 +1,190 @@
+import urlparse
+
+from netloc import Netloc
+from path import URLPath, path_encode, path_decode
+from ports import DEFAULT_PORTS
+from query_string import QueryString
+
+
+class URLObject(unicode):
+
+    """
+    A URL.
+
+    This class contains properties and methods for accessing and modifying the
+    constituent components of a URL. :class:`URLObject` instances are
+    immutable, as they derive from the built-in ``unicode``, and therefore all
+    methods return *new* objects; you need to consider this when using
+    :class:`URLObject` in your own code.
+    """
+
+    def __repr__(self):
+        return 'URLObject(%r)' % (unicode(self),)
+
+    @property
+    def scheme(self):
+        return urlparse.urlsplit(self).scheme
+    def with_scheme(self, scheme):
+        return self.__replace(scheme=scheme)
+
+    @property
+    def netloc(self):
+        return Netloc(urlparse.urlsplit(self).netloc)
+    def with_netloc(self, netloc):
+        return self.__replace(netloc=netloc)
+
+    @property
+    def username(self):
+        return self.netloc.username
+    def with_username(self, username):
+        return self.with_netloc(self.netloc.with_username(username))
+    def without_username(self):
+        return self.with_netloc(self.netloc.without_username())
+
+    @property
+    def password(self):
+        return self.netloc.password
+    def with_password(self, password):
+        return self.with_netloc(self.netloc.with_password(password))
+    def without_password(self):
+        return self.with_netloc(self.netloc.without_password())
+
+    @property
+    def hostname(self):
+        return self.netloc.hostname
+    def with_hostname(self, hostname):
+        return self.with_netloc(self.netloc.with_hostname(hostname))
+
+    @property
+    def port(self):
+        return self.netloc.port
+    def with_port(self, port):
+        return self.with_netloc(self.netloc.with_port(port))
+    def without_port(self):
+        return self.with_netloc(self.netloc.without_port())
+
+    @property
+    def auth(self):
+        return self.netloc.auth
+    def with_auth(self, *auth):
+        return self.with_netloc(self.netloc.with_auth(*auth))
+    def without_auth(self):
+        return self.with_netloc(self.netloc.without_auth())
+
+    @property
+    def default_port(self):
+        """
+        The destination port number for this URL.
+
+        If no port number is explicitly given in the URL, this will return the
+        default port number for the scheme if one is known, or ``None``. The
+        mapping of schemes to default ports is defined in
+        :const:`urlobject.ports.DEFAULT_PORTS`.
+        """
+        port = urlparse.urlsplit(self).port
+        if port is not None:
+            return port
+        return DEFAULT_PORTS.get(self.scheme)
+
+    @property
+    def path(self):
+        return URLPath(urlparse.urlsplit(self).path)
+    def with_path(self, path):
+        return self.__replace(path=path)
+
+    @property
+    def root(self):
+        return self.with_path('/')
+
+    @property
+    def parent(self):
+        return self.with_path(self.path.parent)
+
+    @property
+    def is_leaf(self):
+        return self.path.is_leaf
+
+    def add_path_segment(self, segment):
+        return self.with_path(self.path.add_segment(segment))
+
+    def add_path(self, partial_path):
+        return self.with_path(self.path.add(partial_path))
+
+    @property
+    def query(self):
+        return QueryString(urlparse.urlsplit(self).query)
+    def with_query(self, query):
+        return self.__replace(query=query)
+    def without_query(self):
+        return self.__replace(query='')
+
+    @property
+    def query_list(self):
+        return self.query.list
+
+    @property
+    def query_dict(self):
+        return self.query.dict
+
+    @property
+    def query_multi_dict(self):
+        return self.query.multi_dict
+
+    def add_query_param(self, name, value):
+        return self.with_query(self.query.add_param(name, value))
+    def add_query_params(self, *args, **kwargs):
+        return self.with_query(self.query.add_params(*args, **kwargs))
+
+    def set_query_param(self, name, value):
+        return self.with_query(self.query.set_param(name, value))
+    def set_query_params(self, *args, **kwargs):
+        return self.with_query(self.query.set_params(*args, **kwargs))
+
+    def del_query_param(self, name):
+        return self.with_query(self.query.del_param(name))
+    def del_query_params(self, params):
+        return self.with_query(self.query.del_params(params))
+
+    @property
+    def fragment(self):
+        return path_decode(urlparse.urlsplit(self).fragment)
+    def with_fragment(self, fragment):
+        return self.__replace(fragment=path_encode(fragment))
+    def without_fragment(self):
+        return self.__replace(fragment='')
+
+    def relative(self, other):
+        """Resolve another URL relative to this one."""
+        # Relative URL resolution involves cascading through the properties
+        # from left to right, replacing
+        other = type(self)(other)
+        if other.scheme:
+            return other
+        elif other.netloc:
+            return other.with_scheme(self.scheme)
+        elif other.path:
+            return other.with_scheme(self.scheme).with_netloc(self.netloc) \
+                    .with_path(self.path.relative(other.path))
+        elif other.query:
+            return other.with_scheme(self.scheme).with_netloc(self.netloc) \
+                    .with_path(self.path)
+        elif other.fragment:
+            return other.with_scheme(self.scheme).with_netloc(self.netloc) \
+                    .with_path(self.path).with_query(self.query)
+        # Empty string just removes fragment; it's treated as a path meaning
+        # 'the current location'.
+        return self.without_fragment()
+
+    def __replace(self, **replace):
+        """Replace a field in the ``urlparse.SplitResult`` for this URL."""
+        return type(self)(urlparse.urlunsplit(
+            urlparse.urlsplit(self)._replace(**replace)))
+
+
+if not hasattr(urlparse, 'ResultMixin'):
+    def _replace(split_result, **replace):
+        return urlparse.SplitResult(
+            **dict((attr, replace.get(attr, getattr(split_result, attr)))
+                for attr in ('scheme', 'netloc', 'path', 'query', 'fragment')))
+    urlparse.BaseResult._replace = _replace
+    del _replace