Index: django/utils/httpwrappers.py
===================================================================
--- django/utils/httpwrappers.py	(revision 2623)
+++ django/utils/httpwrappers.py	(working copy)
@@ -2,6 +2,8 @@
 from pprint import pformat
 from urllib import urlencode
 from django.utils.datastructures import MultiValueDict
+import cgi
+from StringIO import StringIO
 
 try:
     # The mod_python version is more efficient, so try importing it first.
@@ -32,35 +34,60 @@
     def get_full_path(self):
         return ''
 
-def parse_file_upload(header_dict, post_data):
+class FileDict(dict):
+    "Keeps uploaded file as file-like object and reads its content on demand"
+    def __getitem__(self, name):
+        if name=='content' and not 'content' in self:
+            self['file'].seek(0, 2)
+            size = self['file'].tell()
+            self['file'].seek(0, 0)
+            self['content']=self['file'].read(size)
+        return dict.__getitem__(self, name)
+
+    def __deepcopy__(self, memo={}):
+        self['content'] # make sure file content is loaded
+        import copy
+        result = self.__class__()
+        memo[id(self)] = result
+        for key, value in dict.items(self):
+            dict.__setitem__(result, copy.deepcopy(key, memo), copy.deepcopy(value, memo))
+        return result
+
+class FieldStorage(cgi.FieldStorage):
+    "cgi.FieldStorage with ability to store files on disk or in memory"
+    def make_file(self, binary=None):
+        from django.conf.settings import STORE_UPLOAD_ON_DISK
+        if STORE_UPLOAD_ON_DISK:
+            return cgi.FieldStorage.make_file(self, binary)
+        else:
+            return StringIO()
+
+def parse_file_upload(post_stream, environ):
     "Returns a tuple of (POST MultiValueDict, FILES MultiValueDict)"
-    import email, email.Message
-    from cgi import parse_header
-    raw_message = '\r\n'.join(['%s:%s' % pair for pair in header_dict.items()])
-    raw_message += '\r\n\r\n' + post_data
-    msg = email.message_from_string(raw_message)
+    fs = FieldStorage(post_stream, environ=environ)
     POST = MultiValueDict()
     FILES = MultiValueDict()
-    for submessage in msg.get_payload():
-        if isinstance(submessage, email.Message.Message):
-            name_dict = parse_header(submessage['Content-Disposition'])[1]
-            # name_dict is something like {'name': 'file', 'filename': 'test.txt'} for file uploads
-            # or {'name': 'blah'} for POST fields
-            # We assume all uploaded files have a 'filename' set.
-            if name_dict.has_key('filename'):
-                assert type([]) != type(submessage.get_payload()), "Nested MIME messages are not supported"
-                if not name_dict['filename'].strip():
+    for key in fs.keys():
+        # We can't use FieldStorage.getlist to get contents of a 
+        # field as list because for file fields it returns only filenames
+        if type(fs[key]) == type([]):
+            field_list = fs[key]
+        else:
+            field_list = [fs[key]]
+        for field in field_list:
+            if hasattr(field, 'filename') and field.filename is not None:
+                if not field.filename.strip():
                     continue
                 # IE submits the full path, so trim everything but the basename.
                 # (We can't use os.path.basename because it expects Linux paths.)
-                filename = name_dict['filename'][name_dict['filename'].rfind("\\")+1:]
-                FILES.appendlist(name_dict['name'], {
+                filename = field.filename[field.filename.rfind("\\")+1:]
+                FILES.appendlist(key, FileDict({
                     'filename': filename,
-                    'content-type': (submessage.has_key('Content-Type') and submessage['Content-Type'] or None),
-                    'content': submessage.get_payload(),
-                })
+                    'content-type': field.type,
+                    'file': field.file,
+                }))
             else:
-                POST.appendlist(name_dict['name'], submessage.get_payload())
+                POST.appendlist(key, field.value)
     return POST, FILES
 
 class QueryDict(MultiValueDict):
Index: django/conf/global_settings.py
===================================================================
--- django/conf/global_settings.py	(revision 2623)
+++ django/conf/global_settings.py	(working copy)
@@ -202,6 +202,10 @@
 # http://psyco.sourceforge.net/
 ENABLE_PSYCO = False
 
+# Whether to store uploaded files in temp files rather than in memory.
+# Storing files on disk may be necessary for accepting large files.
+STORE_UPLOAD_ON_DISK = False
+
 ##############
 # MIDDLEWARE #
 ##############
Index: django/core/handlers/wsgi.py
===================================================================
--- django/core/handlers/wsgi.py	(revision 2623)
+++ django/core/handlers/wsgi.py	(working copy)
@@ -66,9 +66,7 @@
         # Populates self._post and self._files
         if self.environ['REQUEST_METHOD'] == 'POST':
             if self.environ.get('CONTENT_TYPE', '').startswith('multipart'):
-                header_dict = dict([(k, v) for k, v in self.environ.items() if k.startswith('HTTP_')])
-                header_dict['Content-Type'] = self.environ.get('CONTENT_TYPE', '')
-                self._post, self._files = httpwrappers.parse_file_upload(header_dict, self.raw_post_data)
+                self._post, self._files = httpwrappers.parse_file_upload(self.environ['wsgi.input'], self.environ)
             else:
                 self._post, self._files = httpwrappers.QueryDict(self.raw_post_data), datastructures.MultiValueDict()
         else:
Index: django/core/handlers/modpython.py
===================================================================
--- django/core/handlers/modpython.py	(revision 2623)
+++ django/core/handlers/modpython.py	(working copy)
@@ -23,7 +23,10 @@
     def _load_post_and_files(self):
         "Populates self._post and self._files"
         if self._req.headers_in.has_key('content-type') and self._req.headers_in['content-type'].startswith('multipart'):
-            self._post, self._files = httpwrappers.parse_file_upload(self._req.headers_in, self.raw_post_data)
+            environ = dict(self.META)
+            environ['CONTENT_LENGTH'] = environ['HTTP_CONTENT_LENGTH']
+            environ['CONTENT_TYPE'] = environ['HTTP_CONTENT_TYPE']
+            self._post, self._files = httpwrappers.parse_file_upload(self._req, environ)
         else:
             self._post, self._files = httpwrappers.QueryDict(self.raw_post_data), datastructures.MultiValueDict()