diff --git a/changelog.d/3678.misc b/changelog.d/3678.misc
new file mode 100644
index 0000000000..0d7c8da64a
--- /dev/null
+++ b/changelog.d/3678.misc
@@ -0,0 +1 @@
+Rename synapse.util.async to synapse.util.async_helpers to mitigate async becoming a keyword on Python 3.7.
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index e082d45c94..7bbf0ad082 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -40,7 +40,7 @@ from synapse.replication.slave.storage.transactions import TransactionStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
 from synapse.storage.engines import create_engine
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 2b62f687b6..a23136784a 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -40,7 +40,7 @@ from synapse.federation.persistence import TransactionActions
 from synapse.federation.units import Edu, Transaction
 from synapse.http.endpoint import parse_server_name
 from synapse.types import get_domain_from_id
-from synapse.util import async
+from synapse.util.async_helpers import Linearizer, concurrently_execute
 from synapse.util.caches.response_cache import ResponseCache
 from synapse.util.logutils import log_function
 
@@ -67,8 +67,8 @@ class FederationServer(FederationBase):
         self.auth = hs.get_auth()
         self.handler = hs.get_handlers().federation_handler
 
-        self._server_linearizer = async.Linearizer("fed_server")
-        self._transaction_linearizer = async.Linearizer("fed_txn_handler")
+        self._server_linearizer = Linearizer("fed_server")
+        self._transaction_linearizer = Linearizer("fed_txn_handler")
 
         self.transaction_actions = TransactionActions(self.store)
 
@@ -200,7 +200,7 @@ class FederationServer(FederationBase):
                         event_id, f.getTraceback().rstrip(),
                     )
 
-        yield async.concurrently_execute(
+        yield concurrently_execute(
             process_pdus_for_room, pdus_by_room.keys(),
             TRANSACTION_CONCURRENCY_LIMIT,
         )
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 2d44f15da3..9e017116a9 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -23,7 +23,7 @@ from synapse.api.constants import EventTypes
 from synapse.api.errors import FederationDeniedError
 from synapse.types import RoomStreamToken, get_domain_from_id
 from synapse.util import stringutils
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.metrics import measure_func
 from synapse.util.retryutils import NotRetryingDestination
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 0dffd44e22..2380d17f4e 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -52,7 +52,7 @@ from synapse.events.validator import EventValidator
 from synapse.state import resolve_events_with_factory
 from synapse.types import UserID, get_domain_from_id
 from synapse.util import logcontext, unwrapFirstError
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.distributor import user_joined_room
 from synapse.util.frozenutils import unfreeze
 from synapse.util.logutils import log_function
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index 40e7580a61..1fb17fd9a5 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -25,7 +25,7 @@ from synapse.handlers.presence import format_user_presence_state
 from synapse.streams.config import PaginationConfig
 from synapse.types import StreamToken, UserID
 from synapse.util import unwrapFirstError
-from synapse.util.async import concurrently_execute
+from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.snapshot_cache import SnapshotCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.visibility import filter_events_for_client
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index bcb093ba3e..01a362360e 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -32,7 +32,7 @@ from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
 from synapse.replication.http.send_event import ReplicationSendEventRestServlet
 from synapse.types import RoomAlias, UserID
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import measure_func
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index b2849783ed..a97d43550f 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -22,7 +22,7 @@ from synapse.api.constants import Membership
 from synapse.api.errors import SynapseError
 from synapse.events.utils import serialize_event
 from synapse.types import RoomStreamToken
-from synapse.util.async import ReadWriteLock
+from synapse.util.async_helpers import ReadWriteLock
 from synapse.util.logcontext import run_in_background
 from synapse.util.stringutils import random_string
 from synapse.visibility import filter_events_for_client
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 3732830194..20fc3b0323 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -36,7 +36,7 @@ from synapse.api.errors import SynapseError
 from synapse.metrics import LaterGauge
 from synapse.storage.presence import UserPresenceState
 from synapse.types import UserID, get_domain_from_id
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.logcontext import run_in_background
 from synapse.util.logutils import log_function
diff --git a/synapse/handlers/read_marker.py b/synapse/handlers/read_marker.py
index 995460f82a..32108568c6 100644
--- a/synapse/handlers/read_marker.py
+++ b/synapse/handlers/read_marker.py
@@ -17,7 +17,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 
 from ._base import BaseHandler
 
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 0e16bbe0ee..3526b20d5a 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -28,7 +28,7 @@ from synapse.api.errors import (
 )
 from synapse.http.client import CaptchaServerHttpClient
 from synapse.types import RoomAlias, RoomID, UserID, create_requester
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.threepids import check_3pid_allowed
 
 from ._base import BaseHandler
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index 828229f5c3..37e41afd61 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -26,7 +26,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, JoinRules
 from synapse.types import ThirdPartyInstanceID
-from synapse.util.async import concurrently_execute
+from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.caches.response_cache import ResponseCache
 
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 0d4a3f4677..fb94b5d7d4 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -30,7 +30,7 @@ import synapse.types
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import AuthError, Codes, SynapseError
 from synapse.types import RoomID, UserID
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.distributor import user_joined_room, user_left_room
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index dff1f67dcb..6393a9674b 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -25,7 +25,7 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, Membership
 from synapse.push.clientformat import format_push_rules_for_user
 from synapse.types import RoomStreamToken
-from synapse.util.async import concurrently_execute
+from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.response_cache import ResponseCache
diff --git a/synapse/http/client.py b/synapse/http/client.py
index 3771e0b3f6..ab4fbf59b2 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -42,7 +42,7 @@ from twisted.web.http_headers import Headers
 from synapse.api.errors import Codes, HttpResponseException, SynapseError
 from synapse.http import cancelled_to_request_timed_out_error, redact_uri
 from synapse.http.endpoint import SpiderEndpoint
-from synapse.util.async import add_timeout_to_deferred
+from synapse.util.async_helpers import add_timeout_to_deferred
 from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.logcontext import make_deferred_yieldable
 
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 762273f59b..44b61e70a4 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -43,7 +43,7 @@ from synapse.api.errors import (
 from synapse.http import cancelled_to_request_timed_out_error
 from synapse.http.endpoint import matrix_federation_endpoint
 from synapse.util import logcontext
-from synapse.util.async import add_timeout_to_deferred
+from synapse.util.async_helpers import add_timeout_to_deferred
 from synapse.util.logcontext import make_deferred_yieldable
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/notifier.py b/synapse/notifier.py
index e650c3e494..82f391481c 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -25,7 +25,7 @@ from synapse.api.errors import AuthError
 from synapse.handlers.presence import format_user_presence_state
 from synapse.metrics import LaterGauge
 from synapse.types import StreamToken
-from synapse.util.async import (
+from synapse.util.async_helpers import (
     DeferredTimeoutError,
     ObservableDeferred,
     add_timeout_to_deferred,
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index 1d14d3639c..8f9a76147f 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -26,7 +26,7 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, Membership
 from synapse.event_auth import get_user_power_level
 from synapse.state import POWER_KEY
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import register_cache
 from synapse.util.caches.descriptors import cached
 
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index 9d601208fd..bfa6df7b68 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -35,7 +35,7 @@ from synapse.push.presentable_names import (
     name_from_member_event,
 )
 from synapse.types import UserID
-from synapse.util.async import concurrently_execute
+from synapse.util.async_helpers import concurrently_execute
 from synapse.visibility import filter_events_for_client
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/transactions.py b/synapse/rest/client/transactions.py
index 00b1b3066e..511e96ab00 100644
--- a/synapse/rest/client/transactions.py
+++ b/synapse/rest/client/transactions.py
@@ -17,7 +17,7 @@
 to ensure idempotency when performing PUTs using the REST API."""
 import logging
 
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 8fb413d825..4c589e05e0 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -36,7 +36,7 @@ from synapse.api.errors import (
 )
 from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.logcontext import make_deferred_yieldable
 from synapse.util.retryutils import NotRetryingDestination
 from synapse.util.stringutils import is_ascii, random_string
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index 27aa0def2f..778ef97337 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -42,7 +42,7 @@ from synapse.http.server import (
 )
 from synapse.http.servlet import parse_integer, parse_string
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.util.stringutils import is_ascii, random_string
diff --git a/synapse/state.py b/synapse/state.py
index e1092b97a9..8b92d4057a 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -28,7 +28,7 @@ from synapse import event_auth
 from synapse.api.constants import EventTypes
 from synapse.api.errors import AuthError
 from synapse.events.snapshot import EventContext
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logutils import log_function
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index ce32e8fefd..d4aa192a0a 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -38,7 +38,7 @@ from synapse.storage.background_updates import BackgroundUpdateStore
 from synapse.storage.event_federation import EventFederationStore
 from synapse.storage.events_worker import EventsWorkerStore
 from synapse.types import RoomStreamToken, get_domain_from_id
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.logcontext import PreserveLoggingContext, make_deferred_yieldable
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 10dce21cea..9b4e6d6aa8 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -26,7 +26,7 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, Membership
 from synapse.storage.events_worker import EventsWorkerStore
 from synapse.types import get_domain_from_id
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import intern_string
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 from synapse.util.stringutils import to_ascii
diff --git a/synapse/util/async.py b/synapse/util/async_helpers.py
similarity index 100%
rename from synapse/util/async.py
rename to synapse/util/async_helpers.py
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 861c24809c..187510576a 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -25,7 +25,7 @@ from six import itervalues, string_types
 from twisted.internet import defer
 
 from synapse.util import logcontext, unwrapFirstError
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry
diff --git a/synapse/util/caches/response_cache.py b/synapse/util/caches/response_cache.py
index a8491b42d5..afb03b2e1b 100644
--- a/synapse/util/caches/response_cache.py
+++ b/synapse/util/caches/response_cache.py
@@ -16,7 +16,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.caches import register_cache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 
diff --git a/synapse/util/caches/snapshot_cache.py b/synapse/util/caches/snapshot_cache.py
index d03678b8c8..8318db8d2c 100644
--- a/synapse/util/caches/snapshot_cache.py
+++ b/synapse/util/caches/snapshot_cache.py
@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 
 
 class SnapshotCache(object):
diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py
index 8dcae50b39..07e83fadda 100644
--- a/synapse/util/logcontext.py
+++ b/synapse/util/logcontext.py
@@ -526,7 +526,7 @@ _to_ignore = [
     "synapse.util.logcontext",
     "synapse.http.server",
     "synapse.storage._base",
-    "synapse.util.async",
+    "synapse.util.async_helpers",
 ]
 
 
diff --git a/tests/storage/test__base.py b/tests/storage/test__base.py
index 6d6f00c5c5..52eff2a104 100644
--- a/tests/storage/test__base.py
+++ b/tests/storage/test__base.py
@@ -18,7 +18,7 @@ from mock import Mock
 
 from twisted.internet import defer
 
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.caches.descriptors import Cache, cached
 
 from tests import unittest
diff --git a/tests/util/test_linearizer.py b/tests/util/test_linearizer.py
index 4729bd5a0a..7f48a72de8 100644
--- a/tests/util/test_linearizer.py
+++ b/tests/util/test_linearizer.py
@@ -20,7 +20,7 @@ from twisted.internet import defer, reactor
 from twisted.internet.defer import CancelledError
 
 from synapse.util import Clock, logcontext
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 
 from tests import unittest
 
diff --git a/tests/util/test_rwlock.py b/tests/util/test_rwlock.py
index 24194e3b25..7cd470be67 100644
--- a/tests/util/test_rwlock.py
+++ b/tests/util/test_rwlock.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 
 
-from synapse.util.async import ReadWriteLock
+from synapse.util.async_helpers import ReadWriteLock
 
 from tests import unittest