diff --git a/CHANGES.rst b/CHANGES.rst
index f034d37..89cf5f1 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,7 +1,8 @@
 0.5.1 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Add --pull-cache to pull images from repository before building.
+  (`Issue #49 <https://github.com/6si/shipwright/issues/49>`_).
 
 
 0.5.0 (2016-08-19)
diff --git a/shipwright/base.py b/shipwright/base.py
index 213d597..421f1af 100644
--- a/shipwright/base.py
+++ b/shipwright/base.py
@@ -4,10 +4,11 @@ from . import build, dependencies, docker, push
 
 
 class Shipwright(object):
-    def __init__(self, source_control, docker_client, tags):
+    def __init__(self, source_control, docker_client, tags, pull_cache=False):
         self.source_control = source_control
         self.docker_client = docker_client
         self.tags = tags
+        self._pull_cache = pull_cache
 
     def targets(self):
         return self.source_control.targets()
@@ -18,7 +19,10 @@ class Shipwright(object):
         return self._build(this_ref_str, targets)
 
     def _build(self, this_ref_str, targets):
-        for evt in build.do_build(self.docker_client, this_ref_str, targets):
+        client = self.docker_client
+        pull_cache = self._pull_cache
+        ref = this_ref_str
+        for evt in build.do_build(client, ref, targets, pull_cache):
             yield evt
 
         # now that we're built and tagged all the images.
diff --git a/shipwright/build.py b/shipwright/build.py
index 707d4f9..4ee1558 100644
--- a/shipwright/build.py
+++ b/shipwright/build.py
@@ -13,7 +13,7 @@ def _merge(d1, d2):
     return d
 
 
-def do_build(client, build_ref, targets):
+def do_build(client, build_ref, targets, pull_cache):
     """
     Generic function for building multiple images while
     notifying a callback function with output produced.
@@ -39,11 +39,11 @@ def do_build(client, build_ref, targets):
         parent_ref = None
         if target.parent:
             parent_ref = build_index.get(target.parent)
-        for evt in build(client, parent_ref, target):
+        for evt in build(client, parent_ref, target, pull_cache):
             yield evt
 
 
-def build(client, parent_ref, image):
+def build(client, parent_ref, image, pull_cache):
     """
     builds the given image tagged with <build_ref> and ensures that
     it depends on it's parent if it's part of this build group (shares
@@ -62,7 +62,25 @@ def build(client, parent_ref, image):
 
     built_tags = docker.last_built_from_docker(client, image.name)
     if image.ref in built_tags:
-        return []
+        return
+
+    if pull_cache:
+        pull_evts = client.pull(
+            repository=image.name,
+            tag=image.ref,
+            stream=True,
+        )
+
+        failed = False
+        for evt in pull_evts:
+            event = process_event_(evt)
+            if 'error' in event:
+                failed = True
+            else:
+                yield event
+
+        if not failed:
+            return
 
     build_evts = client.build(
         fileobj=mkcontext(parent_ref, image.path),
@@ -73,4 +91,5 @@ def build(client, parent_ref, image):
         dockerfile=os.path.basename(image.path),
     )
 
-    return (process_event_(evt) for evt in build_evts)
+    for evt in build_evts:
+        yield process_event_(evt)
diff --git a/shipwright/cli.py b/shipwright/cli.py
index 24f6f78..82eaf50 100644
--- a/shipwright/cli.py
+++ b/shipwright/cli.py
@@ -109,6 +109,11 @@ def argparser():
         help='Build working tree, including uncommited and untracked changes',
         action='store_true',
     )
+    common.add_argument(
+        '--pull-cache',
+        help='When building try to pull previously built images',
+        action='store_true',
+    )
     a_arg(
         common, '-d', '--dependants',
         help='Build DEPENDANTS and all its dependants',
@@ -157,7 +162,6 @@ def old_style_arg_dict(namespace):
         '--exclude': _flatten(ns.exclude),
         '--help': False,
         '--no-build': getattr(ns, 'no_build', False),
-        '--dirty': getattr(ns, 'dirty', False),
         '--upto': _flatten(ns.upto),
         '--x-assert-hostname': ns.x_assert_hostname,
         '-H': ns.docker_host,
@@ -237,8 +241,10 @@ def run(path, arguments, client_cfg, environ, new_style_args=None):
 
     if new_style_args is None:
         dirty = False
+        pull_cache = False
     else:
         dirty = new_style_args.dirty
+        pull_cache = new_style_args.pull_cache
 
     namespace = config['namespace']
     name_map = config.get('names', {})
@@ -249,7 +255,7 @@ def run(path, arguments, client_cfg, environ, new_style_args=None):
             'to commit these changes, re-run with the --dirty flag.'
         )
 
-    sw = Shipwright(scm, client, arguments['tags'])
+    sw = Shipwright(scm, client, arguments['tags'], pull_cache)
     command = getattr(sw, command_name)
 
     show_progress = sys.stdout.isatty()

diff --git a/tests/integration/test_docker_builds.py b/tests/integration/test_docker_builds.py
index 00aa6be..3a22616 100644
--- a/tests/integration/test_docker_builds.py
+++ b/tests/integration/test_docker_builds.py
@@ -12,7 +12,7 @@ from .utils import commit_untracked, create_repo, get_defaults
 
 
 def default_args():
-    return argparse.Namespace(dirty=False)
+    return argparse.Namespace(dirty=False, pull_cache=False)
 
 
 def test_sample(tmpdir, docker_client):
@@ -734,3 +734,85 @@ def test_build_with_repo_digest(tmpdir, docker_client, registry):
         )
         for image in old_images:
             cli.remove_image(image, force=True)
+
+
+def test_docker_buld_pull_cache(tmpdir, docker_client, registry):
+    path = str(tmpdir.join('shipwright-localhost-sample'))
+    source = pkg_resources.resource_filename(
+        __name__,
+        'examples/shipwright-localhost-sample',
+    )
+    repo = create_repo(path, source)
+    tag = repo.head.ref.commit.hexsha[:12]
+
+    client_cfg = docker_utils.kwargs_from_env()
+    cli = docker_client
+
+    defaults = get_defaults()
+    defaults['push'] = True
+    try:
+        shipw_cli.run(
+            path=path,
+            client_cfg=client_cfg,
+            arguments=defaults,
+            environ={},
+        )
+
+        # Remove the build images:
+        old_images = (
+            cli.images(name='localhost:5000/service1', quiet=True) +
+            cli.images(name='localhost:5000/shared', quiet=True) +
+            cli.images(name='localhost:5000/base', quiet=True)
+        )
+        for image in old_images:
+            cli.remove_image(image, force=True)
+
+        images_after_delete = (
+            cli.images(name='localhost:5000/service1') +
+            cli.images(name='localhost:5000/shared') +
+            cli.images(name='localhost:5000/base')
+        )
+        assert images_after_delete == []
+
+        args = default_args()
+        args.pull_cache = True
+
+        shipw_cli.run(
+            path=path,
+            client_cfg=client_cfg,
+            arguments=defaults,
+            environ={},
+            new_style_args=args,
+        )
+
+        service1, shared, base = (
+            cli.images(name='localhost:5000/service1') +
+            cli.images(name='localhost:5000/shared') +
+            cli.images(name='localhost:5000/base')
+        )
+
+        assert set(service1['RepoTags']) == {
+            'localhost:5000/service1:master',
+            'localhost:5000/service1:latest',
+            'localhost:5000/service1:' + tag,
+        }
+
+        assert set(shared['RepoTags']) == {
+            'localhost:5000/shared:master',
+            'localhost:5000/shared:latest',
+            'localhost:5000/shared:' + tag,
+        }
+
+        assert set(base['RepoTags']) == {
+            'localhost:5000/base:master',
+            'localhost:5000/base:latest',
+            'localhost:5000/base:' + tag,
+        }
+    finally:
+        old_images = (
+            cli.images(name='localhost:5000/service1', quiet=True) +
+            cli.images(name='localhost:5000/shared', quiet=True) +
+            cli.images(name='localhost:5000/base', quiet=True)
+        )
+        for image in old_images:
+            cli.remove_image(image, force=True)
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 260eb92..064f931 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -16,7 +16,6 @@ def get_defaults():
         '--exclude': [],
         '--help': False,
         '--no-build': False,
-        '--dirty': False,
         '--upto': [],
         '--x-assert-hostname': False,
         '-H': None,
@@ -90,7 +89,6 @@ def test_args():
         '--exclude': [],
         '--help': False,
         '--no-build': False,
-        '--dirty': False,
         '--upto': [],
         '--x-assert-hostname': True,
         '-H': None,
@@ -105,7 +103,7 @@ def test_args_2():
     args = [
         '--account=x', '--x-assert-hostname', 'build',
         '-d', 'foo', 'bar',
-        '-t', 'foo', '--dirty',
+        '-t', 'foo', '--dirty', '--pull-cache',
     ]
     parser = cli.argparser()
     arguments = cli.old_style_arg_dict(parser.parse_args(args))
@@ -118,7 +116,6 @@ def test_args_2():
         '--exclude': [],
         '--help': False,
         '--no-build': False,
-        '--dirty': True,
         '--upto': [],
         '--x-assert-hostname': True,
         '-H': None,
@@ -142,7 +139,6 @@ def test_args_base():
         '--exclude': [],
         '--help': False,
         '--no-build': False,
-        '--dirty': False,
         '--upto': [],
         '--x-assert-hostname': False,
         '-H': None,

docker pull all images for current branch and master before building
Because our buildserver forgets the docker cache between builds we pull the previous build for all the images.

it would be great if we could get shipwright to do it.

Otherwise a command like "shipright images" which lists all the images that shipwright *would* build would let us write our own command to do this.
tests/test_cli.py::test_args tests/test_cli.py::test_args_2 tests/test_cli.py::test_args_base
tests/integration/test_docker_builds.py::test_dirty_fails_without_flag tests/test_cli.py::test_without_json_manifest tests/test_cli.py::test_push_also_builds tests/test_cli.py::test_assert_hostname