diff --git a/docker/auth/auth.py b/docker/auth/auth.py
index f0ab7447..59fe1a58 100644
--- a/docker/auth/auth.py
+++ b/docker/auth/auth.py
@@ -87,6 +87,10 @@ def resolve_authconfig(authconfig, registry=None):
     return authconfig.get(swap_protocol(registry), None)
 
 
+def encode_auth(auth_info):
+    return base64.b64encode(auth_info.get('username', '') + b':' +
+                            auth_info.get('password', ''))
+
 def decode_auth(auth):
     if isinstance(auth, six.string_types):
         auth = auth.encode('ascii')
@@ -100,6 +104,12 @@ def encode_header(auth):
     return base64.b64encode(auth_json)
 
 
+def encode_full_header(auth):
+    """ Returns the given auth block encoded for the X-Registry-Config header.
+    """
+    return encode_header({'configs': auth})
+
+
 def load_config(root=None):
     """Loads authentication data from a Docker configuration file in the given
     root directory."""
diff --git a/docker/client.py b/docker/client.py
index 67f4ad09..635ba19d 100644
--- a/docker/client.py
+++ b/docker/client.py
@@ -28,7 +28,7 @@ from .utils import utils
 if not six.PY3:
     import websocket
 
-DEFAULT_DOCKER_API_VERSION = '1.8'
+DEFAULT_DOCKER_API_VERSION = '1.9'
 DEFAULT_TIMEOUT_SECONDS = 60
 STREAM_HEADER_SIZE_BYTES = 8
 
@@ -361,6 +361,17 @@ class Client(requests.Session):
         if context is not None:
             headers = {'Content-Type': 'application/tar'}
 
+        if utils.compare_version('1.9', self._version) >= 0:
+            # If we don't have any auth data so far, try reloading the config
+            # file one more time in case anything showed up in there.
+            if not self._auth_configs:
+                self._auth_configs = auth.load_config()
+
+            # Send the full auth configuration (if any exists), since the build
+            # could use any (or all) of the registries.
+            if self._auth_configs:
+                headers['X-Registry-Config'] = auth.encode_full_header(self._auth_configs)
+
         response = self._post(
             u,
             data=context,
@@ -618,7 +629,7 @@ class Client(requests.Session):
                 self._auth_configs = auth.load_config()
             authcfg = auth.resolve_authconfig(self._auth_configs, registry)
 
-            # Do not fail here if no atuhentication exists for this specific
+            # Do not fail here if no authentication exists for this specific
             # registry as we can have a readonly pull. Just put the header if
             # we can.
             if authcfg:
@@ -644,7 +655,7 @@ class Client(requests.Session):
                 self._auth_configs = auth.load_config()
             authcfg = auth.resolve_authconfig(self._auth_configs, registry)
 
-            # Do not fail here if no atuhentication exists for this specific
+            # Do not fail here if no authentication exists for this specific
             # registry as we can have a readonly pull. Just put the header if
             # we can.
             if authcfg:
diff --git a/tests/integration_test.py b/tests/integration_test.py
index c6189ffb..2f597b15 100644
--- a/tests/integration_test.py
+++ b/tests/integration_test.py
@@ -32,7 +32,7 @@ class BaseTestCase(unittest.TestCase):
     tmp_containers = []
 
     def setUp(self):
-        self.client = docker.Client()
+        self.client = docker.Client(base_url='http://localhost:4243')
         self.client.pull('busybox')
         self.tmp_imgs = []
         self.tmp_containers = []
@@ -755,6 +755,29 @@ class TestBuildFromStringIO(BaseTestCase):
         self.assertNotEqual(logs, '')
 
 
+class TestBuildWithAuth(BaseTestCase):
+    def runTest(self):
+        if self.client._version < 1.9:
+            return
+
+        key = 'K4104GON3P4Q6ZUJFZRRC2ZQTBJ5YT0UMZD7TGT7ZVIR8Y05FAH2TJQI6Y90SMIB'
+        self.client.login('quay+fortesting', key, registry='https://quay.io/v1/', email='')
+
+        script = io.BytesIO('\n'.join([
+            'FROM quay.io/quay/teststuff',
+            'MAINTAINER docker-py',
+            'RUN mkdir -p /tmp/test',
+        ]).encode('ascii'))
+
+        stream = self.client.build(fileobj=script, stream=True)
+        logs = ''
+        for chunk in stream:
+            logs += chunk
+
+        self.assertNotEqual(logs, '')
+        self.assertEqual(logs.find('HTTP code: 403'), -1)
+
+
 #######################
 #  PY SPECIFIC TESTS  #
 #######################
@@ -820,7 +843,7 @@ class TestLoadJSONConfig(BaseTestCase):
 class TestConnectionTimeout(unittest.TestCase):
     def setUp(self):
         self.timeout = 0.5
-        self.client = docker.client.Client(base_url='http://192.168.10.2:4243',
+        self.client = docker.client.Client(base_url='http://localhost:4243',
                                            timeout=self.timeout)
 
     def runTest(self):