diff --git a/tools/semgrep-py.yml b/tools/semgrep-py.yml
index aeaced0be6..b7455550a7 100644
--- a/tools/semgrep-py.yml
+++ b/tools/semgrep-py.yml
@@ -54,6 +54,7 @@ rules:
 
   - id: dont-import-models-in-migrations
     patterns:
+      - pattern-not: from zerver.lib.partial import partial
       - pattern-not: from zerver.lib.mime_types import $X
       - pattern-not: from zerver.lib.redis_utils import get_redis_client
       - pattern-not: from zerver.lib.utils import generate_api_key
diff --git a/zerver/migrations/0576_backfill_imageattachment.py b/zerver/migrations/0576_backfill_imageattachment.py
new file mode 100644
index 0000000000..80d2d8116f
--- /dev/null
+++ b/zerver/migrations/0576_backfill_imageattachment.py
@@ -0,0 +1,126 @@
+import os
+from functools import reduce
+from operator import or_
+
+import boto3
+import pyvips
+from botocore.client import Config
+from botocore.exceptions import ClientError
+from botocore.response import StreamingBody
+from django.conf import settings
+from django.db import migrations
+from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+from django.db.models import Exists, OuterRef, Q
+
+from zerver.lib.partial import partial
+
+
+def backfill_imageattachment(apps: StateApps, schema_editor: BaseDatabaseSchemaEditor) -> None:
+    ImageAttachment = apps.get_model("zerver", "ImageAttachment")
+    Attachment = apps.get_model("zerver", "Attachment")
+
+    if settings.LOCAL_UPLOADS_DIR is None:
+        upload_bucket = boto3.resource(
+            "s3",
+            aws_access_key_id=settings.S3_KEY,
+            aws_secret_access_key=settings.S3_SECRET_KEY,
+            region_name=settings.S3_REGION,
+            endpoint_url=settings.S3_ENDPOINT_URL,
+            config=Config(
+                signature_version=None,
+                s3={"addressing_style": settings.S3_ADDRESSING_STYLE},
+            ),
+        ).Bucket(settings.S3_AUTH_UPLOADS_BUCKET)
+
+    # Historical attachments do not have a mime_type value, so we used
+    # to rely on the file extension.  We replicate that when
+    # backfilling.  This is the value from zerver.lib.markdown:
+    IMAGE_EXTENSIONS = [".bmp", ".gif", ".jpe", ".jpeg", ".jpg", ".png", ".webp"]
+
+    extension_limits = Q()
+    extension_limits = reduce(
+        or_,
+        [Q(file_name__endswith=extension) for extension in IMAGE_EXTENSIONS],
+        extension_limits,
+    )
+
+    min_id: int | None = 0
+    while True:
+        attachments = (
+            Attachment.objects.alias(
+                has_imageattachment=Exists(
+                    ImageAttachment.objects.filter(path_id=OuterRef("path_id"))
+                )
+            )
+            .filter(extension_limits, has_imageattachment=False, id__gt=min_id)
+            .order_by("id")
+        )[:1000]
+
+        min_id = None
+        for attachment in attachments:
+            min_id = attachment.id
+
+            if settings.LOCAL_UPLOADS_DIR is None:
+                try:
+                    metadata = upload_bucket.Object(attachment.path_id).get()
+                except ClientError:
+                    print(f"{attachment.path_id}: Missing!")
+                    continue
+
+                def s3_read(streamingbody: StreamingBody, size: int) -> bytes:
+                    return streamingbody.read(amt=size)
+
+                # We use the streaming body to only pull down as much
+                # of the image as we need to examine the headers --
+                # generally about 40k
+                source: pyvips.Source = pyvips.SourceCustom()
+                source.on_read(partial(s3_read, metadata["Body"]))
+            else:
+                attachment_path = os.path.join(settings.LOCAL_UPLOADS_DIR, attachment.path_id)
+                if not os.path.exists(attachment_path):
+                    print(f"{attachment.path_id}: Missing!")
+                    continue
+                source = pyvips.Source.new_from_file(attachment_path)
+            try:
+                image = pyvips.Image.new_from_source(source, "", access="sequential")
+
+                # "original_width_px" and "original_height_px" here are
+                # _as rendered_, after applying the orientation
+                # information which the image may contain.
+                if (
+                    "orientation" in image.get_fields()
+                    and image.get("orientation") >= 5
+                    and image.get("orientation") <= 8
+                ):
+                    (width, height) = (image.height, image.width)
+                else:
+                    (width, height) = (image.width, image.height)
+
+                ImageAttachment.objects.create(
+                    realm_id=attachment.realm_id,
+                    path_id=attachment.path_id,
+                    original_width_px=width,
+                    original_height_px=height,
+                    frames=image.get_n_pages(),
+                    thumbnail_metadata=[],
+                )
+            except pyvips.Error:
+                pass
+
+        if min_id is None:
+            break
+
+
+class Migration(migrations.Migration):
+    atomic = False
+    dependencies = [
+        # Because this will be backported to 9.x, we only depend on the last migration in 9.x
+        ("zerver", "0558_realmuserdefault_web_animate_image_previews_and_more"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            backfill_imageattachment, reverse_code=migrations.RunPython.noop, elidable=True
+        )
+    ]
diff --git a/zerver/migrations/0577_merge_20240829_0153.py b/zerver/migrations/0577_merge_20240829_0153.py
new file mode 100644
index 0000000000..5f4b255e09
--- /dev/null
+++ b/zerver/migrations/0577_merge_20240829_0153.py
@@ -0,0 +1,10 @@
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("zerver", "0575_alter_directmessagegroup_group_size"),
+        ("zerver", "0576_backfill_imageattachment"),
+    ]
+
+    operations = []