diff --git a/app.py b/app.py
index cf4a055cb..c6c7eecbf 100644
--- a/app.py
+++ b/app.py
@@ -15,6 +15,7 @@ from werkzeug.routing import BaseConverter
 import features
 
 from avatars.avatars import Avatar
+from buildman.manager.buildcanceller import BuildCanceller
 from data import database
 from data import model
 from data.archivedlogs import LogArchive
@@ -196,6 +197,7 @@ superusers = SuperUserManager(app)
 signer = Signer(app, config_provider)
 instance_keys = InstanceKeys(app)
 label_validator = LabelValidator(app)
+build_canceller = BuildCanceller(app)
 
 license_validator = LicenseValidator(config_provider)
 license_validator.start()
diff --git a/buildman/component/buildcomponent.py b/buildman/component/buildcomponent.py
index 59ebf4b67..2b88205df 100644
--- a/buildman/component/buildcomponent.py
+++ b/buildman/component/buildcomponent.py
@@ -246,6 +246,10 @@ class BuildComponent(BaseComponent):
       try:
         if self._build_status.set_phase(phase, log_data.get('status_data')):
           logger.debug('Build %s has entered a new phase: %s', self.builder_realm, phase)
+        elif self._current_job.repo_build.phase == BUILD_PHASE.CANCELLED:
+          build_id = self._current_job.repo_build.uuid
+          logger.debug('Trying to move cancelled build into phase: %s with id: %s', phase, build_id)
+          return False
       except InvalidRepositoryBuildException:
         build_id = self._current_job.repo_build.uuid
         logger.info('Build %s was not found; repo was probably deleted', build_id)
diff --git a/buildman/manager/buildcanceller.py b/buildman/manager/buildcanceller.py
new file mode 100644
index 000000000..87a7996c0
--- /dev/null
+++ b/buildman/manager/buildcanceller.py
@@ -0,0 +1,25 @@
+import logging
+
+from buildman.manager.etcd_canceller import EtcdCanceller
+from buildman.manager.noop_canceller import NoopCanceller
+
+logger = logging.getLogger(__name__)
+
+CANCELLERS = {'ephemeral': EtcdCanceller}
+
+
+class BuildCanceller(object):
+  """ A class to manage cancelling a build """
+
+  def __init__(self, app=None):
+    build_manager_config = app.config.get('BUILD_MANAGER')
+    if app is None or build_manager_config is None:
+      self.handler = NoopCanceller()
+      return
+
+    canceller = CANCELLERS.get(build_manager_config[0], NoopCanceller)
+    self.handler = canceller(build_manager_config[1])
+
+  def try_cancel_build(self, uuid):
+    """ A method to kill a running build """
+    return self.handler.try_cancel_build(uuid)
diff --git a/buildman/manager/etcd_canceller.py b/buildman/manager/etcd_canceller.py
new file mode 100644
index 000000000..dccde1949
--- /dev/null
+++ b/buildman/manager/etcd_canceller.py
@@ -0,0 +1,37 @@
+import logging
+import etcd
+
+logger = logging.getLogger(__name__)
+
+
+class EtcdCanceller(object):
+  """ A class that sends a message to etcd to cancel a build """
+
+  def __init__(self, config):
+    etcd_host = config.get('ETCD_HOST', '127.0.0.1')
+    etcd_port = config.get('ETCD_PORT', 2379)
+    etcd_ca_cert = config.get('ETCD_CA_CERT', None)
+    etcd_auth = config.get('ETCD_CERT_AND_KEY', None)
+    if etcd_auth is not None:
+      etcd_auth = tuple(etcd_auth)
+
+    etcd_protocol = 'http' if etcd_auth is None else 'https'
+    logger.debug('Connecting to etcd on %s:%s', etcd_host, etcd_port)
+    self._cancel_prefix = config.get('ETCD_CANCEL_PREFIX', 'cancel/')
+    self._etcd_client = etcd.Client(
+      host=etcd_host,
+      port=etcd_port,
+      cert=etcd_auth,
+      ca_cert=etcd_ca_cert,
+      protocol=etcd_protocol,
+      read_timeout=5)
+
+  def try_cancel_build(self, build_uuid):
+    """ Writes etcd message to cancel build_uuid. """
+    logger.info("Cancelling build %s".format(build_uuid))
+    try:
+      self._etcd_client.write("{}{}".format(self._cancel_prefix, build_uuid), build_uuid)
+      return True
+    except etcd.EtcdException:
+      logger.exception("Failed to write to etcd client %s", build_uuid)
+      return False
diff --git a/buildman/manager/noop_canceller.py b/buildman/manager/noop_canceller.py
new file mode 100644
index 000000000..2adf17ad7
--- /dev/null
+++ b/buildman/manager/noop_canceller.py
@@ -0,0 +1,8 @@
+class NoopCanceller(object):
+  """ A class that can not cancel a build """
+  def __init__(self, config=None):
+    pass
+
+  def try_cancel_build(self, uuid):
+    """ Does nothing and fails to cancel build. """
+    return False
diff --git a/data/database.py b/data/database.py
index 45aa0daf7..afc1573b4 100644
--- a/data/database.py
+++ b/data/database.py
@@ -741,6 +741,7 @@ class BUILD_PHASE(object):
   PUSHING = 'pushing'
   WAITING = 'waiting'
   COMPLETE = 'complete'
+  CANCELLED = 'cancelled'
 
   @classmethod
   def is_terminal_phase(cls, phase):
diff --git a/data/model/build.py b/data/model/build.py
index 2a22f2f77..13e727edc 100644
--- a/data/model/build.py
+++ b/data/model/build.py
@@ -10,6 +10,8 @@ from data.model import (InvalidBuildTriggerException, InvalidRepositoryBuildExce
 
 
 PRESUMED_DEAD_BUILD_AGE = timedelta(days=15)
+PHASES_NOT_ALLOWED_TO_CANCEL_FROM = (BUILD_PHASE.PUSHING, BUILD_PHASE.COMPLETE,
+                                     BUILD_PHASE.ERROR, BUILD_PHASE.INTERNAL_ERROR)
 
 
 def update_build_trigger(trigger, config, auth_token=None):
@@ -143,54 +145,79 @@ def get_pull_robot_name(trigger):
   return trigger.pull_robot.username
 
 
+def _get_build_row_for_update(build_uuid):
+  return db_for_update(RepositoryBuild.select().where(RepositoryBuild.uuid == build_uuid)).get()
+
+
 def update_phase(build_uuid, phase):
   """ A function to change the phase of a build """
-  with db_transaction():
-    try:
-      build = get_repository_build(build_uuid)
-      build.phase = phase
-      build.save()
-      return True
-    except InvalidRepositoryBuildException:
+  try:
+    build = _get_build_row_for_update(build_uuid)
+  except RepositoryBuild.DoesNotExist:
       return False
 
+  # Can't update a cancelled build
+  if build.phase == BUILD_PHASE.CANCELLED:
+    return False
+
+  build.phase = phase
+  build.save()
+  return True
+
 
 def create_cancel_build_in_queue(build, build_queue):
   """ A function to cancel a build before it leaves the queue """
   def cancel_build():
-    if build.phase != BUILD_PHASE.WAITING or not build.queue_id:
+    cancelled = False
+
+    if build.queue_id is not None:
+      cancelled = build_queue.cancel(build.queue_id)
+
+    if build.phase != BUILD_PHASE.WAITING:
       return False
 
-    cancelled = build_queue.cancel(build.queue_id)
-    if cancelled:
-      # Delete the build row.
-      build.delete_instance()
     return cancelled
 
   return cancel_build
 
 
-def create_cancel_build_in_manager(build):
+def create_cancel_build_in_manager(build, build_canceller):
   """ A function to cancel the build before it starts to push """
   def cancel_build():
-    return False
+    original_phase = build.phase
+    if build.phase in PHASES_NOT_ALLOWED_TO_CANCEL_FROM:
+      return False
+
+    build.phase = BUILD_PHASE.CANCELLED
+    build.save()
+
+    if not build_canceller.try_cancel_build(build.uuid):
+      build.phase = original_phase
+      build.save()
+      return False
+
+    return True
   return cancel_build
 
 
 def cancel_repository_build(build, build_queue):
   """ This tries to cancel the build returns true if request is successful false if it can't be cancelled """
   with db_transaction():
+    from app import build_canceller
     # Reload the build for update.
     # We are loading the build for update so checks should be as quick as possible.
     try:
-      build = db_for_update(RepositoryBuild.select().where(RepositoryBuild.id == build.id)).get()
+      build = _get_build_row_for_update(build.uuid)
     except RepositoryBuild.DoesNotExist:
       return False
 
     cancel_builds = [create_cancel_build_in_queue(build, build_queue),
-                     create_cancel_build_in_manager(build), ]
+                     create_cancel_build_in_manager(build, build_canceller), ]
     for cancelled in cancel_builds:
       if cancelled():
+        # Delete the build row.
+        # TODO Charlie 2016-11-11 Add in message that says build was cancelled and remove the delete build.
+        build.delete_instance()
         return True
 
     return False