diff --git a/eden/mononoke/modern_sync/src/bul_util.rs b/eden/mononoke/modern_sync/src/bul_util.rs
index ba6d5b47c4d9c..79457e0f6dcfd 100644
--- a/eden/mononoke/modern_sync/src/bul_util.rs
+++ b/eden/mononoke/modern_sync/src/bul_util.rs
@@ -15,12 +15,10 @@ use bookmarks::BookmarkUpdateLogEntry;
 use bookmarks::BookmarkUpdateLogId;
 use bookmarks::Freshness;
 use cloned::cloned;
-use commit_graph::CommitGraph;
 use context::CoreContext;
 use futures::stream;
 use futures::stream::StreamExt;
 use futures::stream::TryStreamExt;
-use mononoke_types::ChangesetId;
 
 use crate::sync::ExecutionType;
 
@@ -74,24 +72,3 @@ pub async fn get_one_entry(
 
     stream::iter(entries)
 }
-
-/// Takes a vec of BookmarkUpdateLogEntry and returns a stream of all the ChangesetIds in these movements
-pub async fn get_commit_stream(
-    entries: Vec<BookmarkUpdateLogEntry>,
-    commit_graph: Arc<CommitGraph>,
-    ctx: &CoreContext,
-) -> impl stream::Stream<Item = Result<ChangesetId, Error>> + '_ {
-    let entries_stream = stream::iter(entries);
-    entries_stream
-        .then(move |entry| {
-            cloned!(ctx, commit_graph);
-            async move {
-                let from = entry.from_changeset_id.map_or(vec![], |val| vec![val]);
-                let to = entry.to_changeset_id.map_or(vec![], |val| vec![val]);
-                commit_graph
-                    .ancestors_difference_stream(&ctx, to, from)
-                    .await
-            }
-        })
-        .try_flatten()
-}
diff --git a/eden/mononoke/modern_sync/src/main.rs b/eden/mononoke/modern_sync/src/main.rs
index a4a1f4609311c..f39173e48fd03 100644
--- a/eden/mononoke/modern_sync/src/main.rs
+++ b/eden/mononoke/modern_sync/src/main.rs
@@ -47,11 +47,13 @@ struct ModernSyncArgs {
     #[clap(flatten)]
     tls_params: Option<TLSArgs>,
 
-    #[clap(
-        long,
-        help = "Dest repo name (in case it's different from source repo name)"
-    )]
+    #[clap(long)]
+    /// "Dest repo name (in case it's different from source repo name)"
     dest_repo_name: Option<String>,
+
+    #[clap(long)]
+    /// Update counters in the source repo (prod and tests only)
+    update_counters: bool,
 }
 
 #[facet::container]
diff --git a/eden/mononoke/modern_sync/src/sync.rs b/eden/mononoke/modern_sync/src/sync.rs
index 9ad3cac77b6e0..1d8ee79415ece 100644
--- a/eden/mononoke/modern_sync/src/sync.rs
+++ b/eden/mononoke/modern_sync/src/sync.rs
@@ -18,7 +18,7 @@ use changeset_info::ChangesetInfo;
 use clientinfo::ClientEntryPoint;
 use clientinfo::ClientInfo;
 use cloned::cloned;
-use commit_graph::CommitGraphArc;
+use commit_graph::CommitGraphRef;
 use context::CoreContext;
 use context::SessionContainer;
 use futures::StreamExt;
@@ -121,11 +121,10 @@ pub async fn sync(
                 )
             })?
     };
-
+    let app_args = app.args::<ModernSyncArgs>()?;
     let sender: Arc<dyn ModernSyncSender + Send + Sync> = if dry_run {
         Arc::new(DummySender::new(logger.clone()))
     } else {
-        let app_args = app.args::<ModernSyncArgs>()?;
         let url = if let Some(socket) = app_args.dest_socket {
             // Only for integration tests
             format!("{}:{}/edenapi/", &config.url, socket)
@@ -178,23 +177,35 @@ pub async fn sync(
                     Err(e)
                 }
                 Ok(entries) => {
-                    // TODO: We probably want to get these in inverse order so once we derive the top parent
-                    // the children will already be derived.
-                    bul_util::get_commit_stream(entries, repo.commit_graph_arc(), ctx)
-                        .await
-                        .fuse()
-                        .try_next_step(move |cs_id| {
-                            cloned!(ctx, repo, logger, sender);
-                            async move {
-                                process_one_changeset(&cs_id, &ctx, repo, &logger, sender, false)
+                    for entry in entries {
+                        let from = entry.from_changeset_id.into_iter().collect();
+                        let to = entry.to_changeset_id.into_iter().collect();
+
+                        repo.commit_graph()
+                            .ancestors_difference_stream(ctx, to, from)
+                            .await?
+                            .fuse()
+                            .try_next_step(|cs_id| {
+                                cloned!(ctx, repo, logger, sender);
+                                async move {
+                                    process_one_changeset(
+                                        &cs_id, &ctx, repo, &logger, sender, false,
+                                    )
                                     .await
-                            }
-                        })
-                        .try_collect::<()>()
-                        .await
+                                }
+                            })
+                            .try_collect::<()>()
+                            .await?;
+
+                        if app_args.update_counters {
+                            repo.mutable_counters()
+                                .set_counter(ctx, MODERN_SYNC_COUNTER_NAME, entry.id.0 as i64, None)
+                                .await?;
+                        }
+                    }
+                    Ok(())
                 }
             }
-            // TODO Update counter after processing one entry
         }
     })
     .try_collect::<()>()
diff --git a/eden/mononoke/tests/integration/library.sh b/eden/mononoke/tests/integration/library.sh
index a121d3391b8ae..b0e43a29f8e58 100755
--- a/eden/mononoke/tests/integration/library.sh
+++ b/eden/mononoke/tests/integration/library.sh
@@ -350,6 +350,7 @@ function mononoke_modern_sync {
     "${COMMON_ARGS[@]}" \
     --repo-name "$ORIG_REPO" \
     --dest-repo-name "$DEST_REPO" \
+    --update-counters \
     --mononoke-config-path "$TESTTMP/mononoke-config" \
     --dest-socket $MONONOKE_SOCKET \
     --tls-ca "$TEST_CERTDIR/root-ca.crt" \
diff --git a/eden/mononoke/tests/integration/modern_sync/test-modern-sync.t b/eden/mononoke/tests/integration/modern_sync/test-modern-sync.t
index 18092a53db94e..d5345544bcd6c 100644
--- a/eden/mononoke/tests/integration/modern_sync/test-modern-sync.t
+++ b/eden/mononoke/tests/integration/modern_sync/test-modern-sync.t
@@ -139,6 +139,8 @@ Sync all bookmarks moves
   File HgFileNodeId(HgNodeHash(Sha1(35e7525ce3a48913275d7061dd9a867ffef1e34d)))
   File HgFileNodeId(HgNodeHash(Sha1(778675f9ec8d35ff2fce23a34f68edd15d783853)))
 
+  $ mononoke_admin mutable-counters --repo-name orig get modern_sync
+  Some(2)
   $ cat  $TESTTMP/modern_sync_scuba_logs | jq | rg "start_id|dry_run|repo"
       "start_id": 0,
       "dry_run": "false",