diff --git a/tools/backfill-issue-snapshots.sql b/tools/backfill-issue-snapshots.sql
new file mode 100644
index 0000000..d60ff77
--- /dev/null
+++ b/tools/backfill-issue-snapshots.sql
@@ -0,0 +1,260 @@
+-- Copyright 2018 The Chromium Authors. All Rights Reserved.
+--
+-- Use of this source code is governed by a BSD-style
+-- license that can be found in the LICENSE file or at
+-- https://developers.google.com/open-source/licenses/bsd
+
+
+DROP PROCEDURE IF EXISTS BackfillIssueSnapshotsCcs;
+DROP PROCEDURE IF EXISTS BackfillIssueSnapshotsComponents;
+DROP PROCEDURE IF EXISTS BackfillIssueSnapshotsLabels;
+DROP PROCEDURE IF EXISTS BackfillIssueSnapshotsHotlists;
+DROP PROCEDURE IF EXISTS BackfillIssueSnapshotsChunk;
+DROP PROCEDURE IF EXISTS BackfillIssueSnapshotsManyChunks;
+
+delimiter //
+
+CREATE PROCEDURE BackfillIssueSnapshotsLabels(IN c_issue_id INT, IN c_issuesnapshot_id INT)
+BEGIN
+
+  DECLARE done INT DEFAULT FALSE;
+
+  DECLARE c_label_id INT;
+
+  DECLARE curs CURSOR FOR
+    SELECT label_id
+    FROM Issue2Label
+    WHERE issue_id = c_issue_id;
+
+  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
+  OPEN curs;
+
+  label_loop: LOOP
+    FETCH curs INTO c_label_id;
+    IF done THEN
+      LEAVE label_loop;
+    END IF;
+
+    INSERT INTO IssueSnapshot2Label
+      (issuesnapshot_id, label_id)
+      VALUES
+      (c_issuesnapshot_id, c_label_id);
+
+  END LOOP;
+
+  CLOSE curs;
+END;
+
+
+CREATE PROCEDURE BackfillIssueSnapshotsCcs(IN c_issue_id INT, IN c_issuesnapshot_id INT)
+BEGIN
+
+  DECLARE done INT DEFAULT FALSE;
+
+  DECLARE c_cc_id INT UNSIGNED;
+
+  DECLARE curs CURSOR FOR
+    SELECT cc_id
+    FROM Issue2Cc
+    WHERE issue_id = c_issue_id;
+
+  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
+  OPEN curs;
+
+  cc_loop: LOOP
+    FETCH curs INTO c_cc_id;
+    IF done THEN
+      LEAVE cc_loop;
+    END IF;
+
+    INSERT INTO IssueSnapshot2Cc
+      (issuesnapshot_id, cc_id)
+      VALUES
+      (c_issuesnapshot_id, c_cc_id);
+
+  END LOOP;
+
+  CLOSE curs;
+END;
+
+
+CREATE PROCEDURE BackfillIssueSnapshotsComponents(IN c_issue_id INT, IN c_issuesnapshot_id INT)
+BEGIN
+
+  DECLARE done INT DEFAULT FALSE;
+
+  DECLARE c_component_id INT;
+
+  DECLARE curs CURSOR FOR
+    SELECT component_id
+    FROM Issue2Component
+    WHERE issue_id = c_issue_id;
+
+  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
+  OPEN curs;
+
+  component_loop: LOOP
+    FETCH curs INTO c_component_id;
+    IF done THEN
+      LEAVE component_loop;
+    END IF;
+
+    INSERT INTO IssueSnapshot2Component
+      (issuesnapshot_id, component_id)
+      VALUES
+      (c_issuesnapshot_id, c_component_id);
+
+  END LOOP;
+
+  CLOSE curs;
+END;
+
+
+CREATE PROCEDURE BackfillIssueSnapshotsHotlists(IN c_issue_id INT, IN c_issuesnapshot_id INT)
+BEGIN
+
+  DECLARE done INT DEFAULT FALSE;
+
+  DECLARE c_hotlist_id INT;
+
+  DECLARE curs CURSOR FOR
+    SELECT hotlist_id
+    FROM Hotlist2Issue
+    WHERE issue_id = c_issue_id;
+
+  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
+  OPEN curs;
+
+  hotlist_loop: LOOP
+    FETCH curs INTO c_hotlist_id;
+    IF done THEN
+      LEAVE hotlist_loop;
+    END IF;
+
+    INSERT INTO IssueSnapshot2Hotlist
+      (issuesnapshot_id, hotlist_id)
+      VALUES
+      (c_issuesnapshot_id, c_hotlist_id);
+
+  END LOOP;
+
+  CLOSE curs;
+END;
+
+
+CREATE PROCEDURE BackfillIssueSnapshotsChunk(IN chunk_size INT UNSIGNED,
+  IN chunk_offset INT UNSIGNED)
+BEGIN
+
+  DECLARE done TINYINT DEFAULT FALSE;
+
+  DECLARE c_issue_id INT;
+  DECLARE c_issue_shard INT;
+  DECLARE c_issue_project_id INT;
+  DECLARE c_issue_local_id INT;
+  DECLARE c_issue_status_id INT;
+  DECLARE c_issue_opened INT;
+  DECLARE c_issue_closed INT;
+  DECLARE c_issue_is_open BOOLEAN;
+  DECLARE c_reporter_id INT UNSIGNED;
+  DECLARE c_owner_id INT UNSIGNED;
+  DECLARE c_issuesnapshot_id INT;
+  DECLARE total_counter INT UNSIGNED DEFAULT 0;
+  DECLARE write_counter INT UNSIGNED DEFAULT 0;
+
+  DECLARE curs CURSOR FOR
+    SELECT i.id, i.shard, i.project_id, i.local_id, i.status_id, i.opened,
+      -- If a snapshot for this Issue already exists, make the new snapshot's
+      -- period_end the period_start of the existing snapshot.
+      (SELECT IFNULL((
+          SELECT period_start
+          FROM IssueSnapshot
+          WHERE issue_id = i.id
+          ORDER BY period_start ASC
+          LIMIT 1
+      ), 4294967295)),
+      sd.means_open,
+      i.reporter_id, i.owner_id
+    FROM Issue i
+    JOIN StatusDef sd ON i.status_id = sd.id
+    WHERE i.id >= chunk_offset AND i.id < chunk_offset + chunk_size;
+
+  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
+
+  OPEN curs;
+
+  issue_loop: LOOP
+    FETCH curs INTO c_issue_id, c_issue_shard, c_issue_project_id,
+      c_issue_local_id, c_issue_status_id, c_issue_opened, c_issue_closed,
+      c_issue_is_open, c_reporter_id, c_owner_id;
+    IF done THEN
+      SELECT 'Final chunk status',
+        c_issue_id AS 'Processing Issue ID:',
+        total_counter AS 'Issues fetched',
+        write_counter AS 'Snapshots written';
+      LEAVE issue_loop;
+    END IF;
+
+    -- Indicate progress.
+    IF (SELECT c_issue_id % 100 = 0) THEN
+      SELECT 'Chunk status',
+        c_issue_id AS 'Processing Issue ID:',
+        total_counter AS 'Issues fetched',
+        write_counter AS 'Snapshots written';
+    END IF;
+
+    SET total_counter = total_counter + 1;
+
+    INSERT INTO IssueSnapshot
+    (issue_id, shard, project_id, local_id, status_id, period_start,
+    period_end, is_open, reporter_id, owner_id)
+    VALUES
+    (c_issue_id, c_issue_shard, c_issue_project_id,
+    c_issue_local_id, c_issue_status_id, c_issue_opened,
+    c_issue_closed, c_issue_is_open, c_reporter_id, c_owner_id);
+
+    SET write_counter = write_counter + 1;
+
+    SET c_issuesnapshot_id = LAST_INSERT_ID();
+    -- Add a tiny sleep here to reduce replication pressure on write.
+    SET @throwaway = (SELECT SLEEP(0.1));
+
+    -- Backfill labels.
+    CALL BackfillIssueSnapshotsLabels(c_issue_id, c_issuesnapshot_id);
+    CALL BackfillIssueSnapshotsCcs(c_issue_id, c_issuesnapshot_id);
+    CALL BackfillIssueSnapshotsComponents(c_issue_id, c_issuesnapshot_id);
+    CALL BackfillIssueSnapshotsHotlists(c_issue_id, c_issuesnapshot_id);
+
+  END LOOP;
+
+  CLOSE curs;
+END;
+
+
+CREATE PROCEDURE BackfillIssueSnapshotsManyChunks(
+  IN num_chunks SMALLINT UNSIGNED,
+  IN chunk_size SMALLINT UNSIGNED)
+BEGIN
+  DECLARE chunk_i INT DEFAULT 0;
+
+  -- Handle no results found ("cursor is not open")
+  DECLARE CONTINUE HANDLER FOR SQLSTATE '24000' BEGIN END;
+
+  WHILE chunk_i < num_chunks DO
+
+    SELECT CONCAT('Backfilling chunk ', chunk_i + 1, ' of ', num_chunks) AS '';
+    SELECT chunk_size, chunk_i, chunk_i * chunk_size AS 'chunk offset';
+
+    CALL BackfillIssueSnapshotsChunk(chunk_size, chunk_i * chunk_size);
+
+    SELECT SLEEP(1);
+
+    SET chunk_i = chunk_i + 1;
+  END WHILE;
+END;
+
+
+//
+
+
+delimiter ;