diff --git a/swh/journal/cli.py b/swh/journal/cli.py
--- a/swh/journal/cli.py
+++ b/swh/journal/cli.py
@@ -11,9 +11,11 @@
 from swh.core import config
 from swh.core.cli import CONTEXT_SETTINGS
 from swh.storage import get_storage
+from swh.objstorage import get_objstorage
 
 from swh.journal.client import JournalClient
 from swh.journal.replay import process_replay_objects
+from swh.journal.replay import process_replay_objects_content
 from swh.journal.backfill import JournalBackfiller
 
 
@@ -136,6 +138,68 @@
         ctx.exit(0)
 
 
+@cli.command()
+@click.option('--broker', 'brokers', type=str, multiple=True,
+              hidden=True,  # prefer config file
+              help='Kafka broker to connect to.')
+@click.option('--prefix', type=str, default=None,
+              hidden=True,  # prefer config file
+              help='Prefix of Kafka topic names to read from.')
+@click.option('--group-id', '--consumer-id', type=str,
+              hidden=True,  # prefer config file
+              help='Name of the consumer/group id for reading from Kafka.')
+@click.pass_context
+def content_replay(ctx, brokers, prefix, group_id):
+    """Fill a destination Object Storage (typically a mirror) by reading a Journal
+    and retrieving objects from an existing source ObjStorage.
+
+    There can be several 'replayers' filling a given ObjStorage as long as they
+    use the same `group-id`.
+
+    This service retrieves object ids to copy from the 'content' topic. It will
+    only copy object's content if the object's description in the kafka
+    nmessage has the status:visible set.
+    """
+    logger = logging.getLogger(__name__)
+    conf = ctx.obj['config']
+    try:
+        objstorage_src = get_objstorage(**conf.pop('objstorage_src'))
+    except KeyError:
+        ctx.fail('You must have a source objstorage configured in '
+                 'your config file.')
+    try:
+        objstorage_dst = get_objstorage(**conf.pop('objstorage_dst'))
+    except KeyError:
+        ctx.fail('You must have a destination objstorage configured '
+                 'in your config file.')
+
+    if brokers is None:
+        brokers = conf.get('journal', {}).get('brokers')
+    if not brokers:
+        ctx.fail('You must specify at least one kafka broker.')
+
+    if prefix is None:
+        prefix = conf.get('journal', {}).get('prefix')
+
+    if group_id is None:
+        group_id = conf.get('journal', {}).get('group_id')
+
+    client = JournalClient(brokers=brokers, group_id=group_id, prefix=prefix)
+    worker_fn = functools.partial(process_replay_objects_content,
+                                  src=objstorage_src,
+                                  dst=objstorage_dst)
+
+    try:
+        nb_messages = 0
+        while True:
+            nb_messages += client.process(worker_fn)
+            logger.info('Processed %d messages.' % nb_messages)
+    except KeyboardInterrupt:
+        ctx.exit(0)
+    else:
+        print('Done.')
+
+
 def main():
     logging.basicConfig()
     return cli(auto_envvar_prefix='SWH_JOURNAL')
diff --git a/swh/journal/replay.py b/swh/journal/replay.py
--- a/swh/journal/replay.py
+++ b/swh/journal/replay.py
@@ -6,6 +6,7 @@
 import logging
 
 from swh.storage import HashCollision
+from swh.objstorage.objstorage import ID_HASH_ALGO
 
 
 logger = logging.getLogger(__name__)
@@ -39,3 +40,16 @@
             for obj in objects])
     else:
         assert False
+
+
+def process_replay_objects_content(all_objects, *, src, dst):
+    for (object_type, objects) in all_objects.items():
+        if object_type != 'content':
+            logger.warning('Received a series of %s, this should not happen',
+                           object_type)
+            continue
+        for obj in objects:
+            if obj['status'] == 'visible':
+                obj_id = obj[ID_HASH_ALGO]
+                obj = src.get(obj_id)
+                dst.add(obj, obj_id=obj_id)
diff --git a/swh/journal/tests/test_cli.py b/swh/journal/tests/test_cli.py
--- a/swh/journal/tests/test_cli.py
+++ b/swh/journal/tests/test_cli.py
@@ -85,3 +85,6 @@
 
     assert storage.snapshot_get(snapshot['id']) == {
         **snapshot, 'next_branch': None}
+
+
+# TODO: write a test for the content-replay command
diff --git a/swh/journal/tests/test_write_replay.py b/swh/journal/tests/test_write_replay.py
--- a/swh/journal/tests/test_write_replay.py
+++ b/swh/journal/tests/test_write_replay.py
@@ -16,6 +16,7 @@
 from swh.journal.client import JournalClient, ACCEPTED_OBJECT_TYPES
 from swh.journal.direct_writer import DirectKafkaWriter
 from swh.journal.replay import process_replay_objects
+from swh.journal.replay import process_replay_objects_content
 from swh.journal.serializers import (
     key_to_kafka, kafka_to_key, value_to_kafka, kafka_to_value)
 
@@ -101,3 +102,32 @@
 
 
 # TODO: add test for hash collision
+
+
+@given(lists(object_dicts(), min_size=1))
+@settings(suppress_health_check=[HealthCheck.too_slow])
+def test_write_replay_content(objects):
+    queue = []
+    replayer = MockedJournalClient(queue)
+
+    storage1 = Storage()
+    storage1.journal_writer = MockedKafkaWriter(queue)
+
+    for (obj_type, obj) in objects:
+        obj = obj.copy()
+        if obj_type == 'content':
+            storage1.content_add([obj])
+
+    queue_size = sum(len(partition)
+                     for batch in queue
+                     for partition in batch.values())
+
+    storage2 = Storage()
+    worker_fn = functools.partial(process_replay_objects_content,
+                                  src=storage1.objstorage,
+                                  dst=storage2.objstorage)
+    nb_messages = 0
+    while nb_messages < queue_size:
+        nb_messages += replayer.process(worker_fn)
+
+    assert storage1.objstorage.state == storage2.objstorage.state