diff --git a/Lib/xml/dom/xmlbuilder.py b/Lib/xml/dom/xmlbuilder.py
new file mode 100644
index 0000000..fd43c37
--- /dev/null
+++ b/Lib/xml/dom/xmlbuilder.py
@@ -0,0 +1,388 @@
+"""Implementation of the DOM Level 3 'LS-Load' feature."""
+
+import copy
+import xml.dom
+
+from xml.dom.minicompat import *
+
+from xml.dom.NodeFilter import NodeFilter
+
+
+__all__ = ["DOMBuilder", "DOMEntityResolver", "DOMInputSource"]
+
+
+class Options:
+    """Features object that has variables set for each DOMBuilder feature.
+
+    The DOMBuilder class uses an instance of this class to pass settings to
+    the ExpatBuilder class.
+    """
+
+    # Note that the DOMBuilder class in LoadSave constrains which of these
+    # values can be set using the DOM Level 3 LoadSave feature.
+
+    namespaces = 1
+    namespace_declarations = True
+    validation = False
+    external_parameter_entities = True
+    external_general_entities = True
+    external_dtd_subset = True
+    validate_if_schema = False
+    validate = False
+    datatype_normalization = False
+    create_entity_ref_nodes = True
+    entities = True
+    whitespace_in_element_content = True
+    cdata_sections = True
+    comments = True
+    charset_overrides_xml_encoding = True
+    infoset = False
+    supported_mediatypes_only = False
+
+    errorHandler = None
+    filter = None
+
+
+class DOMBuilder:
+    entityResolver = None
+    errorHandler = None
+    filter = None
+
+    ACTION_REPLACE = 1
+    ACTION_APPEND_AS_CHILDREN = 2
+    ACTION_INSERT_AFTER = 3
+    ACTION_INSERT_BEFORE = 4
+
+    _legal_actions = (ACTION_REPLACE, ACTION_APPEND_AS_CHILDREN,
+                      ACTION_INSERT_AFTER, ACTION_INSERT_BEFORE)
+
+    def __init__(self):
+        self._options = Options()
+
+    def _get_entityResolver(self):
+        return self.entityResolver
+    def _set_entityResolver(self, entityResolver):
+        self.entityResolver = entityResolver
+
+    def _get_errorHandler(self):
+        return self.errorHandler
+    def _set_errorHandler(self, errorHandler):
+        self.errorHandler = errorHandler
+
+    def _get_filter(self):
+        return self.filter
+    def _set_filter(self, filter):
+        self.filter = filter
+
+    def setFeature(self, name, state):
+        if self.supportsFeature(name):
+            state = state and 1 or 0
+            try:
+                settings = self._settings[(_name_xform(name), state)]
+            except KeyError:
+                raise xml.dom.NotSupportedErr(
+                    "unsupported feature: " + `name`)
+            else:
+                for name, value in settings:
+                    setattr(self._options, name, value)
+        else:
+            raise xml.dom.NotFoundErr("unknown feature: " + repr(name))
+
+    def supportsFeature(self, name):
+        return hasattr(self._options, _name_xform(name))
+
+    def canSetFeature(self, name, state):
+        key = (_name_xform(name), state and 1 or 0)
+        return self._settings.has_key(key)
+
+    # This dictionary maps from (feature,value) to a list of
+    # (option,value) pairs that should be set on the Options object.
+    # If a (feature,value) setting is not in this dictionary, it is
+    # not supported by the DOMBuilder.
+    #
+    _settings = {
+        ("namespace_declarations", 0): [
+            ("namespace_declarations", 0)],
+        ("namespace_declarations", 1): [
+            ("namespace_declarations", 1)],
+        ("validation", 0): [
+            ("validation", 0)],
+        ("external_general_entities", 0): [
+            ("external_general_entities", 0)],
+        ("external_general_entities", 1): [
+            ("external_general_entities", 1)],
+        ("external_parameter_entities", 0): [
+            ("external_parameter_entities", 0)],
+        ("external_parameter_entities", 1): [
+            ("external_parameter_entities", 1)],
+        ("validate_if_schema", 0): [
+            ("validate_if_schema", 0)],
+        ("create_entity_ref_nodes", 0): [
+            ("create_entity_ref_nodes", 0)],
+        ("create_entity_ref_nodes", 1): [
+            ("create_entity_ref_nodes", 1)],
+        ("entities", 0): [
+            ("create_entity_ref_nodes", 0),
+            ("entities", 0)],
+        ("entities", 1): [
+            ("entities", 1)],
+        ("whitespace_in_element_content", 0): [
+            ("whitespace_in_element_content", 0)],
+        ("whitespace_in_element_content", 1): [
+            ("whitespace_in_element_content", 1)],
+        ("cdata_sections", 0): [
+            ("cdata_sections", 0)],
+        ("cdata_sections", 1): [
+            ("cdata_sections", 1)],
+        ("comments", 0): [
+            ("comments", 0)],
+        ("comments", 1): [
+            ("comments", 1)],
+        ("charset_overrides_xml_encoding", 0): [
+            ("charset_overrides_xml_encoding", 0)],
+        ("charset_overrides_xml_encoding", 1): [
+            ("charset_overrides_xml_encoding", 1)],
+        ("infoset", 0): [],
+        ("infoset", 1): [
+            ("namespace_declarations", 0),
+            ("validate_if_schema", 0),
+            ("create_entity_ref_nodes", 0),
+            ("entities", 0),
+            ("cdata_sections", 0),
+            ("datatype_normalization", 1),
+            ("whitespace_in_element_content", 1),
+            ("comments", 1),
+            ("charset_overrides_xml_encoding", 1)],
+        ("supported_mediatypes_only", 0): [
+            ("supported_mediatypes_only", 0)],
+        ("namespaces", 0): [
+            ("namespaces", 0)],
+        ("namespaces", 1): [
+            ("namespaces", 1)],
+    }
+
+    def getFeature(self, name):
+        xname = _name_xform(name)
+        try:
+            return getattr(self._options, xname)
+        except AttributeError:
+            if name == "infoset":
+                options = self._options
+                return (options.datatype_normalization
+                        and options.whitespace_in_element_content
+                        and options.comments
+                        and options.charset_overrides_xml_encoding
+                        and not (options.namespace_declarations
+                                 or options.validate_if_schema
+                                 or options.create_entity_ref_nodes
+                                 or options.entities
+                                 or options.cdata_sections))
+            raise xml.dom.NotFoundErr("feature %s not known" % repr(name))
+
+    def parseURI(self, uri):
+        if self.entityResolver:
+            input = self.entityResolver.resolveEntity(None, uri)
+        else:
+            input = DOMEntityResolver().resolveEntity(None, uri)
+        return self.parse(input)
+
+    def parse(self, input):
+        options = copy.copy(self._options)
+        options.filter = self.filter
+        options.errorHandler = self.errorHandler
+        fp = input.byteStream
+        if fp is None and options.systemId:
+            import urllib2
+            fp = urllib2.urlopen(input.systemId)
+        return self._parse_bytestream(fp, options)
+
+    def parseWithContext(self, input, cnode, action):
+        if action not in self._legal_actions:
+            raise ValueError("not a legal action")
+        raise NotImplementedError("Haven't written this yet...")
+
+    def _parse_bytestream(self, stream, options):
+        import xml.dom.expatbuilder
+        builder = xml.dom.expatbuilder.makeBuilder(options)
+        return builder.parseFile(stream)
+
+
+def _name_xform(name):
+    return name.lower().replace('-', '_')
+
+
+class DOMEntityResolver(NewStyle):
+    __slots__ = '_opener',
+
+    def resolveEntity(self, publicId, systemId):
+        assert systemId is not None
+        source = DOMInputSource()
+        source.publicId = publicId
+        source.systemId = systemId
+        source.byteStream = self._get_opener().open(systemId)
+
+        # determine the encoding if the transport provided it
+        source.encoding = self._guess_media_encoding(source)
+
+        # determine the base URI is we can
+        import posixpath, urlparse
+        parts = urlparse.urlparse(systemId)
+        scheme, netloc, path, params, query, fragment = parts
+        # XXX should we check the scheme here as well?
+        if path and not path.endswith("/"):
+            path = posixpath.dirname(path) + "/"
+            parts = scheme, netloc, path, params, query, fragment
+            source.baseURI = urlparse.urlunparse(parts)
+
+        return source
+
+    def _get_opener(self):
+        try:
+            return self._opener
+        except AttributeError:
+            self._opener = self._create_opener()
+            return self._opener
+
+    def _create_opener(self):
+        import urllib2
+        return urllib2.build_opener()
+
+    def _guess_media_encoding(self, source):
+        info = source.byteStream.info()
+        if info.has_key("Content-Type"):
+            for param in info.getplist():
+                if param.startswith("charset="):
+                    return param.split("=", 1)[1].lower()
+
+
+class DOMInputSource(NewStyle):
+    __slots__ = ('byteStream', 'characterStream', 'stringData',
+                 'encoding', 'publicId', 'systemId', 'baseURI')
+
+    def __init__(self):
+        self.byteStream = None
+        self.characterStream = None
+        self.stringData = None
+        self.encoding = None
+        self.publicId = None
+        self.systemId = None
+        self.baseURI = None
+
+    def _get_byteStream(self):
+        return self.byteStream
+    def _set_byteStream(self, byteStream):
+        self.byteStream = byteStream
+
+    def _get_characterStream(self):
+        return self.characterStream
+    def _set_characterStream(self, characterStream):
+        self.characterStream = characterStream
+
+    def _get_stringData(self):
+        return self.stringData
+    def _set_stringData(self, data):
+        self.stringData = data
+
+    def _get_encoding(self):
+        return self.encoding
+    def _set_encoding(self, encoding):
+        self.encoding = encoding
+
+    def _get_publicId(self):
+        return self.publicId
+    def _set_publicId(self, publicId):
+        self.publicId = publicId
+
+    def _get_systemId(self):
+        return self.systemId
+    def _set_systemId(self, systemId):
+        self.systemId = systemId
+
+    def _get_baseURI(self):
+        return self.baseURI
+    def _set_baseURI(self, uri):
+        self.baseURI = uri
+
+
+class DOMBuilderFilter:
+    """Element filter which can be used to tailor construction of
+    a DOM instance.
+    """
+
+    # There's really no need for this class; concrete implementations
+    # should just implement the endElement() and startElement()
+    # methods as appropriate.  Using this makes it easy to only
+    # implement one of them.
+
+    FILTER_ACCEPT = 1
+    FILTER_REJECT = 2
+    FILTER_SKIP = 3
+    FILTER_INTERRUPT = 4
+
+    whatToShow = NodeFilter.SHOW_ALL
+
+    def _get_whatToShow(self):
+        return self.whatToShow
+
+    def acceptNode(self, element):
+        return self.FILTER_ACCEPT
+
+    def startContainer(self, element):
+        return self.FILTER_ACCEPT
+
+del NodeFilter
+
+
+class DocumentLS:
+    """Mixin to create documents that conform to the load/save spec."""
+
+    async = False
+
+    def _get_async(self):
+        return False
+    def _set_async(self, async):
+        if async:
+            raise xml.dom.NotSupportedErr(
+                "asynchronous document loading is not supported")
+
+    def abort(self):
+        # What does it mean to "clear" a document?  Does the
+        # documentElement disappear?
+        raise NotImplementedError(
+            "haven't figured out what this means yet")
+
+    def load(self, uri):
+        raise NotImplementedError("haven't written this yet")
+
+    def loadXML(self, source):
+        raise NotImplementedError("haven't written this yet")
+
+    def saveXML(self, snode):
+        if snode is None:
+            snode = self
+        elif snode.ownerDocument is not self:
+            raise xml.dom.WrongDocumentErr()
+        return snode.toxml()
+
+
+class DOMImplementationLS:
+    MODE_SYNCHRONOUS = 1
+    MODE_ASYNCHRONOUS = 2
+
+    def createDOMBuilder(self, mode, schemaType):
+        if schemaType is not None:
+            raise xml.dom.NotSupportedErr(
+                "schemaType not yet supported")
+        if mode == self.MODE_SYNCHRONOUS:
+            return DOMBuilder()
+        if mode == self.MODE_ASYNCHRONOUS:
+            raise xml.dom.NotSupportedErr(
+                "asynchronous builders are not supported")
+        raise ValueError("unknown value for mode")
+
+    def createDOMWriter(self):
+        raise NotImplementedError(
+            "the writer interface hasn't been written yet!")
+
+    def createDOMInputSource(self):
+        return DOMInputSource()