diff --git a/eden/scm/edenscm/hgext/hgsql.py b/eden/scm/edenscm/hgext/hgsql.py
index c922ca380e..72bcb532fe 100644
--- a/eden/scm/edenscm/hgext/hgsql.py
+++ b/eden/scm/edenscm/hgext/hgsql.py
@@ -1116,6 +1116,17 @@ def wraprepo(repo):
                 self._filecache.pop("manifestlog", None)
                 self._filecache.pop("_phasecache", None)
 
+                # hgsql only writes to revlogs. Sync revlog to zstore.
+                # This is for test compatibility. Do not use it in production.
+                if "zstorecommitdata" in self.storerequirements:
+                    if not util.istest():
+                        raise error.Abort(
+                            _(
+                                "zstore commit data is forbidden for hgsql production use due to performance concerns"
+                            )
+                        )
+                    self._syncrevlogtozstore()
+
                 # Refill the cache. We can't just reuse the exact contents of
                 # the old cached ctx, since the old ctx contains a reference to
                 # the old revlog, which is now out of date.
diff --git a/eden/scm/edenscm/mercurial/configitems.py b/eden/scm/edenscm/mercurial/configitems.py
index 4e14670bf5..25efd932c1 100644
--- a/eden/scm/edenscm/mercurial/configitems.py
+++ b/eden/scm/edenscm/mercurial/configitems.py
@@ -311,6 +311,9 @@ coreconfigitem("format", "obsstore-version", default=None)
 coreconfigitem("format", "usefncache", default=True)
 coreconfigitem("format", "usegeneraldelta", default=True)
 coreconfigitem("format", "usestore", default=True)
+coreconfigitem("format", "use-zstore-commit-data", default=False)
+coreconfigitem("format", "use-zstore-commit-data-revlog-fallback", default=False)
+coreconfigitem("format", "use-zstore-commit-data-server-fallback", default=False)
 coreconfigitem("fsmonitor", "warn_when_unused", default=True)
 coreconfigitem("fsmonitor", "warn_update_file_count", default=50000)
 coreconfigitem("hint", "ack", default=list)
diff --git a/eden/scm/edenscm/mercurial/helptext.py b/eden/scm/edenscm/mercurial/helptext.py
index 162890566c..449c64dd44 100644
--- a/eden/scm/edenscm/mercurial/helptext.py
+++ b/eden/scm/edenscm/mercurial/helptext.py
@@ -1101,6 +1101,23 @@ Example for ``~/.hgrc``::
 
     Enabled by default.
 
+``use-zstore-commit-data``
+
+    Use zstore (a SHA1 content store) to store commit metadata (user, date,
+    message, extras, but not the parent order). This makes it that
+    "00changelog.d" is no longer used for reading commits content. If
+    "00changelog.i" is still used, "00changelog.d" is still written to when
+    adding new commits.
+
+``use-zstore-commit-data-revlog-fallback``
+
+    When data is not found in zstore, fallback to lookup in revlog.
+
+``use-zstore-commit-data-server-fallback``
+
+    When data is not found in zstore, fallback to lookup from the server.
+    (Not implemented yet)
+
 ``dirstate``
     Dirstate format version to use. One of 0 (flat dirstate), 1
     (treedirstate), and 2 (treestate). Default is 1.
diff --git a/eden/scm/edenscm/mercurial/hg.py b/eden/scm/edenscm/mercurial/hg.py
index bc4660113f..efe12ed707 100644
--- a/eden/scm/edenscm/mercurial/hg.py
+++ b/eden/scm/edenscm/mercurial/hg.py
@@ -678,6 +678,13 @@ def clone(
                 raise
 
             destlock = copystore(ui, srcrepo, destpath)
+            # repo initialization might also take a lock. Keeping destlock
+            # outside the repo object can cause deadlock. To avoid deadlock,
+            # we just release destlock here. The lock will be re-acquired
+            # soon by `destpeer`, or `local.lock()` below.
+            if destlock is not None:
+                destlock.release()
+
             # copy bookmarks over
             srcbookmarks = srcrepo.svfs.join("bookmarks")
             dstbookmarks = os.path.join(destpath, "store", "bookmarks")
@@ -688,11 +695,6 @@ def clone(
             # into it
             destpeer = peer(srcrepo, peeropts, dest)
             srcrepo.hook("outgoing", source="clone", node=node.hex(node.nullid))
-            # Attach "destlock" to the repo. So 'repo.lock()' wouldn't
-            # deadlock. wlock needs to be taken first.
-            if destlock:
-                destlockw = destpeer.local().wlock()
-                destpeer.local()._lockref = weakref.ref(destlock)
         else:
             try:
                 destpeer = peer(srcrepo or ui, peeropts, dest, create=True)
@@ -755,6 +757,8 @@ def clone(
                 fp.close()
 
                 destrepo.ui.setconfig("paths", "default", defaulturl, "clone")
+                if destrepo.ui.configbool("format", "use-zstore-commit-data"):
+                    destrepo._syncrevlogtozstore()
 
                 if update:
                     if update is not True:
diff --git a/eden/scm/edenscm/mercurial/localrepo.py b/eden/scm/edenscm/mercurial/localrepo.py
index 05da21d565..ed6a87a01c 100644
--- a/eden/scm/edenscm/mercurial/localrepo.py
+++ b/eden/scm/edenscm/mercurial/localrepo.py
@@ -20,6 +20,8 @@ import random
 import time
 import weakref
 
+# pyre-fixme[21]: Could not find `bindings`.
+import bindings
 from edenscm.hgext.extlib.phabricator import diffprops
 
 from . import (
@@ -52,6 +54,7 @@ from . import (
     pathutil,
     peer,
     phases,
+    progress,
     pushkey,
     pycompat,
     repository,
@@ -356,7 +359,7 @@ class localrepository(object):
         "treestate",
         "storerequirements",
     }
-    _basestoresupported = {"visibleheads", "narrowheads"}
+    _basestoresupported = {"visibleheads", "narrowheads", "zstorecommitdata"}
     openerreqs = {"revlogv1", "generaldelta", "treemanifest"}
 
     # sets of (ui, featureset) functions for repo and store features.
@@ -588,6 +591,7 @@ class localrepository(object):
                     self.svfs.write(name, self.sharedvfs.read(name))
 
         self._narrowheadsmigration()
+        self._zstorecommitdatamigration()
 
     def _narrowheadsmigration(self):
         """Migrate if 'narrow-heads' config has changed."""
@@ -648,6 +652,58 @@ class localrepository(object):
                     self.storerequirements.remove("narrowheads")
                     self._writestorerequirements()
 
+    def _zstorecommitdatamigration(self):
+        """Migrate if 'narrow-heads' config has changed."""
+        zstorecommitdatadesired = self.ui.configbool("format", "use-zstore-commit-data")
+        zstorecommitdatacurrent = "zstorecommitdata" in self.storerequirements
+        if zstorecommitdatadesired != zstorecommitdatacurrent:
+            if zstorecommitdatadesired:
+                # Migrating up. Read all commits in revlog and store them in
+                # zstore.
+                with self.lock():
+                    self._syncrevlogtozstore()
+                    self.storerequirements.add("zstorecommitdata")
+                    self._writestorerequirements()
+            else:
+                # Migrating down is just removing the store requirement.
+                with self.lock():
+                    self.storerequirements.remove("zstorecommitdata")
+                    self._writestorerequirements()
+
+    def _syncrevlogtozstore(self):
+        """Sync commit data from revlog to zstore"""
+        zstore = bindings.zstore.zstore(self.svfs.join("hgcommits/v1"))
+        self.unfiltered().changelog.zstore = zstore
+
+        if self.ui.configbool(
+            "format", "use-zstore-commit-data-revlog-fallback"
+        ) or self.ui.configbool("format", "use-zstore-commit-data-server-fallback"):
+            return
+
+        with progress.bar(
+            self.ui, _("migrating commit data"), _("commits"), len(self)
+        ) as prog:
+            cl = self.changelog
+            cl.zstore = None
+            textwithheader = revlog.textwithheader
+            clrevision = cl.revision
+            clparents = cl.parents
+            clnode = cl.node
+            insert = zstore.insert
+            contains = zstore.__contains__
+            for rev in self:
+                prog.value += 1
+                node = clnode(rev)
+                if contains(node):
+                    continue
+                text = clrevision(rev)
+                p1, p2 = clparents(node)
+                newnode = insert(textwithheader(text, p1, p2))
+                assert node == newnode
+                if (rev + 1) % 1000000 == 0:
+                    zstore.flush()
+            zstore.flush()
+
     @property
     def vfs(self):
         self.ui.develwarn(
@@ -852,10 +908,15 @@ class localrepository(object):
     @storecache("00changelog.i", "visibleheads", "remotenames")
     def changelog(self):
         def loadchangelog(self):
+            if "zstorecommitdata" in self.storerequirements:
+                zstore = bindings.zstore.zstore(self.svfs.join("hgcommits/v1"))
+            else:
+                zstore = None
             return changelog.changelog(
                 self.svfs,
                 uiconfig=self.ui.uiconfig(),
                 trypending=txnutil.mayhavesharedpending(self.root, self.sharedroot),
+                zstore=zstore,
             )
 
         cl = loadchangelog(self)
@@ -1317,6 +1378,11 @@ class localrepository(object):
 
         def releasefn(tr, success):
             repo = reporef()
+            # Flush changelog zstore unconditionally. This makes the commit
+            # data available even if the transaction gets rolled back.
+            zstore = repo.changelog.zstore
+            if zstore is not None:
+                zstore.flush()
             if success:
                 # this should be explicitly invoked here, because
                 # in-memory changes aren't written out at closing
@@ -2661,4 +2727,7 @@ def newrepostorerequirements(repo):
     if ui.configbool("experimental", "narrow-heads"):
         requirements.add("narrowheads")
 
+    if ui.configbool("format", "use-zstore-commit-data"):
+        requirements.add("zstorecommitdata")
+
     return requirements
diff --git a/eden/scm/edenscm/mercurial/streamclone.py b/eden/scm/edenscm/mercurial/streamclone.py
index 5c6ab7553f..e0c064e435 100644
--- a/eden/scm/edenscm/mercurial/streamclone.py
+++ b/eden/scm/edenscm/mercurial/streamclone.py
@@ -162,6 +162,9 @@ def maybeperformlegacystreamclone(pullop):
 
         repo.invalidate()
 
+        if "zstorecommitdata" in repo.storerequirements:
+            repo._syncrevlogtozstore()
+
     return True
 
 
diff --git a/eden/scm/tests/test-fb-hgext-fixcorrupt.t b/eden/scm/tests/test-fb-hgext-fixcorrupt.t
index 013cfd17b0..8be47f1347 100644
--- a/eden/scm/tests/test-fb-hgext-fixcorrupt.t
+++ b/eden/scm/tests/test-fb-hgext-fixcorrupt.t
@@ -4,6 +4,11 @@
   $ SKIPREMOTEFILELOGCHECK=1
   $ export SKIPREMOTEFILELOGCHECK
 
+The fixcorrupt extension fixes pure revlog-based changelog. It is incompatible
+with zstore-baked changelog.d:
+
+  $ setconfig format.use-zstore-commit-data=false
+
   $ cat > noinline.py << EOF
   > from edenscm.mercurial import revlog
   > revlog.REVLOG_DEFAULT_FLAGS = 0
diff --git a/eden/scm/tests/test-help.t b/eden/scm/tests/test-help.t
index 7fdd413cfb..50b54b1528 100644
--- a/eden/scm/tests/test-help.t
+++ b/eden/scm/tests/test-help.t
@@ -1212,6 +1212,12 @@ Separate sections from subsections
   
       "usestore"
   
+      "use-zstore-commit-data"
+  
+      "use-zstore-commit-data-revlog-fallback"
+  
+      "use-zstore-commit-data-server-fallback"
+  
       "dirstate"
   
       "uselz4"
diff --git a/eden/scm/tests/test-verify.t b/eden/scm/tests/test-verify.t
index 4048a5b357..425dec5ced 100644
--- a/eden/scm/tests/test-verify.t
+++ b/eden/scm/tests/test-verify.t
@@ -1,6 +1,11 @@
 #chg-compatible
 
   $ setconfig extensions.treemanifest=!
+
+Verify works on revlog repos. It is incompatible with zstore-backed changelog.d:
+
+  $ setconfig format.use-zstore-commit-data=false
+
 prepare repo
 
   $ hg init a
diff --git a/eden/scm/tests/test-zstore-commit-data-migration-t.py b/eden/scm/tests/test-zstore-commit-data-migration-t.py
new file mode 100644
index 0000000000..9fec034706
--- /dev/null
+++ b/eden/scm/tests/test-zstore-commit-data-migration-t.py
@@ -0,0 +1,87 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2.
+
+from __future__ import absolute_import
+
+from testutil.dott import feature, sh, testtmp  # noqa: F401
+
+
+# Test turning zstore-commit-data on and off
+
+sh % "setconfig format.use-zstore-commit-data=off"
+
+sh % "newrepo"
+sh % "drawdag" << r"""
+B C
+|/
+A
+"""
+
+# Migrate up (double-writes to zstore and 00changelog.d).
+
+sh % "setconfig format.use-zstore-commit-data=on"
+sh % 'hg log -r "$C" -T "{desc}\\n"' == "C"
+
+# Create new commits.
+
+sh % "drawdag" << r"""
+  F
+ /|
+D E
+| |
+desc(C)
+"""
+
+# With zstore-commit-data, 00changelog.d is not used for reading commits.
+
+sh % "mv .hg/store/00changelog.d .hg/store/00changelog.d.bak"
+sh % 'hg log -GT "{desc}"' == r"""
+    o    F
+    |\
+    | o  E
+    | |
+    o |  D
+    |/
+    o  C
+    |
+    | o  B
+    |/
+    o  A"""
+
+# Migrate down. 00changelog.d becomes required.
+
+sh % "setconfig format.use-zstore-commit-data=off"
+sh % 'hg log -GT "{desc}"' == r"""
+    abort: *00changelog.d* (glob)
+    [255]"""
+
+sh % "mv .hg/store/00changelog.d.bak .hg/store/00changelog.d"
+sh % 'hg log -GT "{desc}"' == r"""
+    o    F
+    |\
+    | o  E
+    | |
+    o |  D
+    |/
+    o  C
+    |
+    | o  B
+    |/
+    o  A"""
+
+# Create new commits.
+
+sh % "drawdag" << r"""
+H
+|
+G
+|
+desc(B)
+"""
+
+# Migrate up (double-writes to zstore and 00changelog.d).
+
+sh % "setconfig format.use-zstore-commit-data=on"
+sh % 'hg log -r "$H" -T "{desc}\\n"' == "H"