diff --git a/hgext/infinitepush/__init__.py b/hgext/infinitepush/__init__.py
--- a/hgext/infinitepush/__init__.py
+++ b/hgext/infinitepush/__init__.py
@@ -91,13 +91,11 @@ import collections
 import contextlib
 import errno
 import functools
-import json
 import logging
 import os
 import random
 import re
 import socket
-import struct
 import subprocess
 import sys
 import tempfile
@@ -682,19 +680,6 @@ def _lookupwrap(orig):
                     return "%s %s\n" % (0, r)
     return _lookup
 
-def _decodebookmarks(stream):
-    sizeofjsonsize = struct.calcsize('>i')
-    size = struct.unpack('>i', stream.read(sizeofjsonsize))[0]
-    unicodedict = json.loads(stream.read(size))
-    # python json module always returns unicode strings. We need to convert
-    # it back to bytes string
-    result = {}
-    for bookmark, node in unicodedict.iteritems():
-        bookmark = bookmark.encode('ascii')
-        node = node.encode('ascii')
-        result[bookmark] = node
-    return result
-
 def _update(orig, ui, repo, node=None, rev=None, **opts):
     if rev and node:
         raise error.Abort(_("please specify just one revision"))
@@ -985,7 +970,6 @@ def partgen(pushop, bundler):
     return handlereply
 
 bundle2.capabilities[bundleparts.scratchbranchparttype] = ()
-bundle2.capabilities[bundleparts.scratchbookmarksparttype] = ()
 
 def _getrevs(bundle, oldnode, force, bookmark):
     'extracts and validates the revs to be imported'
@@ -1059,7 +1043,6 @@ def processparts(orig, repo, op, unbundl
 
     bundler = bundle2.bundle20(repo.ui)
     cgparams = None
-    scratchbookpart = None
     with bundle2.partiterator(repo, op, unbundler) as parts:
         for part in parts:
             bundlepart = None
@@ -1084,14 +1067,6 @@ def processparts(orig, repo, op, unbundl
                     op.records.add(scratchbranchparttype + '_skippushkey', True)
                     op.records.add(scratchbranchparttype + '_skipphaseheads',
                                    True)
-            elif part.type == bundleparts.scratchbookmarksparttype:
-                # Save this for later processing. Details below.
-                #
-                # Upstream https://phab.mercurial-scm.org/D1389 and its
-                # follow-ups stop part.seek support to reduce memory usage
-                # (https://bz.mercurial-scm.org/5691). So we need to copy
-                # the part so it can be consumed later.
-                scratchbookpart = bundleparts.copiedpart(part)
             else:
                 if handleallparts or part.type in partforwardingwhitelist:
                     # Ideally we would not process any parts, and instead just
@@ -1137,12 +1112,6 @@ def processparts(orig, repo, op, unbundl
                 # we would rather see the original exception
                 pass
 
-    # The scratch bookmark part is sent as part of a push backup. It needs to be
-    # processed after the main bundle has been stored, so that any commits it
-    # references are available in the store.
-    if scratchbookpart:
-        bundle2._processpart(op, scratchbookpart)
-
 def storebundle(op, params, bundlefile):
     log = _getorcreateinfinitepushlogger(op)
     parthandlerstart = time.time()
@@ -1269,26 +1238,6 @@ def bundle2scratchbranch(op, part):
 
     return 1
 
-@bundle2.parthandler(bundleparts.scratchbookmarksparttype)
-def bundle2scratchbookmarks(op, part):
-    '''Handler deletes bookmarks first then adds new bookmarks.
-    '''
-    index = op.repo.bundlestore.index
-    decodedbookmarks = _decodebookmarks(part)
-    toinsert = {}
-    todelete = []
-    for bookmark, node in decodedbookmarks.iteritems():
-        if node:
-            toinsert[bookmark] = node
-        else:
-            todelete.append(bookmark)
-    log = _getorcreateinfinitepushlogger(op)
-    with logservicecall(log, bundleparts.scratchbookmarksparttype), index:
-        if todelete:
-            index.deletebookmarks(todelete)
-        if toinsert:
-            index.addmanybookmarks(toinsert)
-
 def _maybeaddpushbackpart(op, bookmark, newnode, oldnode, params):
     if params.get('pushbackbookmarks'):
         if op.reply and 'pushback' in op.reply.capabilities:
diff --git a/hgext/infinitepush/bundleparts.py b/hgext/infinitepush/bundleparts.py
--- a/hgext/infinitepush/bundleparts.py
+++ b/hgext/infinitepush/bundleparts.py
@@ -18,11 +18,9 @@ from mercurial import (
 
 from . import common
 
-encodebookmarks = common.encodebookmarks
 isremotebooksenabled = common.isremotebooksenabled
 
 scratchbranchparttype = 'b2x:infinitepush'
-scratchbookmarksparttype = 'b2x:infinitepushscratchbookmarks'
 
 def getscratchbranchparts(repo, peer, outgoing, confignonforwardmove,
                          ui, bookmark, create):
@@ -85,15 +83,6 @@ def getscratchbranchparts(repo, peer, ou
 
     return parts
 
-def getscratchbookmarkspart(peer, bookmarks):
-    if scratchbookmarksparttype not in bundle2.bundle2caps(peer):
-        raise error.Abort(
-            _('no server support for %r') % scratchbookmarksparttype)
-
-    return bundle2.bundlepart(
-        scratchbookmarksparttype.upper(),
-        data=encodebookmarks(bookmarks))
-
 def _validaterevset(repo, revset, bookmark):
     """Abort if the revs to be pushed aren't valid for a scratch branch."""
     if not repo.revs(revset):
diff --git a/hgext/infinitepush/common.py b/hgext/infinitepush/common.py
--- a/hgext/infinitepush/common.py
+++ b/hgext/infinitepush/common.py
@@ -5,9 +5,7 @@
 
 from __future__ import absolute_import
 
-import json
 import os
-import struct
 import tempfile
 
 from mercurial.node import hex
@@ -21,14 +19,6 @@ def isremotebooksenabled(ui):
     return ('remotenames' in extensions._extensions and
             ui.configbool('remotenames', 'bookmarks'))
 
-def encodebookmarks(bookmarks):
-    encoded = {}
-    for bookmark, node in bookmarks.iteritems():
-        encoded[bookmark] = node
-    dumped = json.dumps(encoded)
-    result = struct.pack('>i', len(dumped)) + dumped
-    return result
-
 def downloadbundle(repo, unknownbinhead):
     index = repo.bundlestore.index
     store = repo.bundlestore.store