diff --git a/src/applications/harbormaster/application/PhabricatorHarbormasterApplication.php b/src/applications/harbormaster/application/PhabricatorHarbormasterApplication.php
--- a/src/applications/harbormaster/application/PhabricatorHarbormasterApplication.php
+++ b/src/applications/harbormaster/application/PhabricatorHarbormasterApplication.php
@@ -60,12 +60,13 @@
           'delete/(?:(?P<id>\d+)/)?' => 'HarbormasterStepDeleteController',
         ),
         'buildable/' => array(
-          '(?P<id>\d+)/(?P<action>stop|resume|restart)/'
+          '(?P<id>\d+)/(?P<action>stop|resume|restart|abort)/'
             => 'HarbormasterBuildableActionController',
         ),
         'build/' => array(
           '(?P<id>\d+)/' => 'HarbormasterBuildViewController',
-          '(?P<action>stop|resume|restart)/(?P<id>\d+)/(?:(?P<via>[^/]+)/)?'
+          '(?P<action>stop|resume|restart|abort)/'.
+            '(?P<id>\d+)/(?:(?P<via>[^/]+)/)?'
             => 'HarbormasterBuildActionController',
         ),
         'plan/' => array(
diff --git a/src/applications/harbormaster/controller/HarbormasterBuildActionController.php b/src/applications/harbormaster/controller/HarbormasterBuildActionController.php
--- a/src/applications/harbormaster/controller/HarbormasterBuildActionController.php
+++ b/src/applications/harbormaster/controller/HarbormasterBuildActionController.php
@@ -41,6 +41,9 @@
       case HarbormasterBuildCommand::COMMAND_RESUME:
         $can_issue = $build->canResumeBuild();
         break;
+      case HarbormasterBuildCommand::COMMAND_ABORT:
+        $can_issue = $build->canAbortBuild();
+        break;
       default:
         return new Aphront400Response();
     }
@@ -90,6 +93,18 @@
           }
         }
         break;
+      case HarbormasterBuildCommand::COMMAND_ABORT:
+        if ($can_issue) {
+          $title = pht('Really abort build?');
+          $body = pht(
+            'Progress on this build will be discarded.  Really '.
+            'abort build?');
+          $submit = pht('Abort Build');
+        } else {
+          $title = pht('Unable to Abort Build');
+          $body = pht('You can not abort this build.');
+        }
+        break;
       case HarbormasterBuildCommand::COMMAND_STOP:
         if ($can_issue) {
           $title = pht('Really pause build?');
diff --git a/src/applications/harbormaster/controller/HarbormasterBuildViewController.php b/src/applications/harbormaster/controller/HarbormasterBuildViewController.php
--- a/src/applications/harbormaster/controller/HarbormasterBuildViewController.php
+++ b/src/applications/harbormaster/controller/HarbormasterBuildViewController.php
@@ -39,6 +39,8 @@
       $header->setStatus('fa-exclamation-triangle', 'red', pht('Pausing'));
     } else if ($build->isResuming()) {
       $header->setStatus('fa-exclamation-triangle', 'red', pht('Resuming'));
+    } else if ($build->isAborting()) {
+      $header->setStatus('fa-exclamation-triangle', 'red', pht('Aborting'));
     }
 
     $box = id(new PHUIObjectBoxView())
@@ -415,6 +417,7 @@
     $can_restart = $build->canRestartBuild();
     $can_stop = $build->canStopBuild();
     $can_resume = $build->canResumeBuild();
+    $can_abort = $build->canAbortBuild();
 
     $list->addAction(
       id(new PhabricatorActionView())
@@ -442,6 +445,14 @@
           ->setWorkflow(true));
     }
 
+    $list->addAction(
+      id(new PhabricatorActionView())
+        ->setName(pht('Abort Build'))
+        ->setIcon('fa-exclamation-triangle')
+        ->setHref($this->getApplicationURI('/build/abort/'.$id.'/'))
+        ->setDisabled(!$can_abort)
+        ->setWorkflow(true));
+
     return $list;
   }
 
diff --git a/src/applications/harbormaster/controller/HarbormasterBuildableActionController.php b/src/applications/harbormaster/controller/HarbormasterBuildableActionController.php
--- a/src/applications/harbormaster/controller/HarbormasterBuildableActionController.php
+++ b/src/applications/harbormaster/controller/HarbormasterBuildableActionController.php
@@ -49,6 +49,11 @@
             $issuable[] = $build;
           }
           break;
+        case HarbormasterBuildCommand::COMMAND_ABORT:
+          if ($build->canAbortBuild()) {
+            $issuable[] = $build;
+          }
+          break;
         default:
           return new Aphront400Response();
       }
@@ -110,6 +115,17 @@
           $body = pht('No builds can be stopped.');
         }
         break;
+      case HarbormasterBuildCommand::COMMAND_ABORT:
+        if ($issuable) {
+          $title = pht('Really abort all builds?');
+          $body = pht(
+            'If you abort all builds, work will halt immediately.');
+          $submit = pht('Abort All Builds');
+        } else {
+          $title = pht('Unable to Abort Builds');
+          $body = pht('No builds can be aborted.');
+        }
+        break;
       case HarbormasterBuildCommand::COMMAND_RESUME:
         if ($issuable) {
           $title = pht('Really resume all builds?');
diff --git a/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php b/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php
--- a/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php
+++ b/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php
@@ -85,6 +85,7 @@
     $can_restart = false;
     $can_resume = false;
     $can_stop = false;
+    $can_abort = false;
 
     foreach ($buildable->getBuilds() as $build) {
       if ($build->canRestartBuild()) {
@@ -96,11 +97,15 @@
       if ($build->canStopBuild()) {
         $can_stop = true;
       }
+      if ($build->canAbortBuild()) {
+        $can_abort = true;
+      }
     }
 
     $restart_uri = "buildable/{$id}/restart/";
     $stop_uri = "buildable/{$id}/stop/";
     $resume_uri = "buildable/{$id}/resume/";
+    $abort_uri = "buildable/{$id}/abort/";
 
     $list->addAction(
       id(new PhabricatorActionView())
@@ -126,6 +131,14 @@
         ->setWorkflow(true)
         ->setDisabled(!$can_resume || !$can_edit));
 
+    $list->addAction(
+      id(new PhabricatorActionView())
+        ->setIcon('fa-exclamation-triangle')
+        ->setName(pht('Abort All Builds'))
+        ->setHref($this->getApplicationURI($abort_uri))
+        ->setWorkflow(true)
+        ->setDisabled(!$can_abort || !$can_edit));
+
     return $list;
   }
 
@@ -190,6 +203,7 @@
       $restart_uri = "build/restart/{$build_id}/buildable/";
       $resume_uri = "build/resume/{$build_id}/buildable/";
       $stop_uri = "build/stop/{$build_id}/buildable/";
+      $abort_uri = "build/abort/{$build_id}/buildable/";
 
       $item->addAction(
         id(new PHUIListItemView())
diff --git a/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php b/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
--- a/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
+++ b/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
@@ -77,6 +77,9 @@
       case HarbormasterBuildCommand::COMMAND_RESUME:
         $issuable = $build->canResumeBuild();
         break;
+      case HarbormasterBuildCommand::COMMAND_ABORT:
+        $issuable = $build->canAbortBuild();
+        break;
       default:
         throw new Exception(pht('Unknown command %s', $command));
     }
diff --git a/src/applications/harbormaster/engine/HarbormasterBuildEngine.php b/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
--- a/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
+++ b/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
@@ -98,21 +98,27 @@
   }
 
   private function updateBuild(HarbormasterBuild $build) {
-    if (($build->getBuildStatus() == HarbormasterBuild::STATUS_PENDING) ||
-        ($build->isRestarting())) {
+    if ($build->isAborting()) {
       $this->restartBuild($build);
-      $build->setBuildStatus(HarbormasterBuild::STATUS_BUILDING);
+      $build->setBuildStatus(HarbormasterBuild::STATUS_ABORTED);
       $build->save();
-    }
+    } else {
+      if (($build->getBuildStatus() == HarbormasterBuild::STATUS_PENDING) ||
+          ($build->isRestarting())) {
+        $this->restartBuild($build);
+        $build->setBuildStatus(HarbormasterBuild::STATUS_BUILDING);
+        $build->save();
+      }
 
-    if ($build->isResuming()) {
-      $build->setBuildStatus(HarbormasterBuild::STATUS_BUILDING);
-      $build->save();
-    }
+      if ($build->isResuming()) {
+        $build->setBuildStatus(HarbormasterBuild::STATUS_BUILDING);
+        $build->save();
+      }
 
-    if ($build->isStopping() && !$build->isComplete()) {
-      $build->setBuildStatus(HarbormasterBuild::STATUS_STOPPED);
-      $build->save();
+      if ($build->isStopping() && !$build->isComplete()) {
+        $build->setBuildStatus(HarbormasterBuild::STATUS_STOPPED);
+        $build->save();
+      }
     }
 
     $build->deleteUnprocessedCommands();
diff --git a/src/applications/harbormaster/storage/HarbormasterBuildCommand.php b/src/applications/harbormaster/storage/HarbormasterBuildCommand.php
--- a/src/applications/harbormaster/storage/HarbormasterBuildCommand.php
+++ b/src/applications/harbormaster/storage/HarbormasterBuildCommand.php
@@ -5,6 +5,7 @@
   const COMMAND_STOP = 'stop';
   const COMMAND_RESUME = 'resume';
   const COMMAND_RESTART = 'restart';
+  const COMMAND_ABORT = 'abort';
 
   protected $authorPHID;
   protected $targetPHID;
diff --git a/src/applications/harbormaster/storage/HarbormasterBuildTransaction.php b/src/applications/harbormaster/storage/HarbormasterBuildTransaction.php
--- a/src/applications/harbormaster/storage/HarbormasterBuildTransaction.php
+++ b/src/applications/harbormaster/storage/HarbormasterBuildTransaction.php
@@ -31,6 +31,10 @@
             return pht(
               '%s restarted this build.',
               $this->renderHandleLink($author_phid));
+          case HarbormasterBuildCommand::COMMAND_ABORT:
+            return pht(
+              '%s aborted this build.',
+              $this->renderHandleLink($author_phid));
           case HarbormasterBuildCommand::COMMAND_RESUME:
             return pht(
               '%s resumed this build.',
@@ -61,6 +65,8 @@
             return 'fa-play';
           case HarbormasterBuildCommand::COMMAND_STOP:
             return 'fa-stop';
+          case HarbormasterBuildCommand::COMMAND_ABORT:
+            return 'fa-exclamation-triangle';
         }
     }
 
@@ -79,6 +85,7 @@
       case self::TYPE_COMMAND:
         switch ($new) {
           case HarbormasterBuildCommand::COMMAND_STOP:
+          case HarbormasterBuildCommand::COMMAND_ABORT:
             return 'red';
         }
     }
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuild.php b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuild.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
@@ -42,6 +42,11 @@
   const STATUS_FAILED = 'failed';
 
   /**
+   * The build has aborted.
+   */
+  const STATUS_ABORTED = 'aborted';
+
+  /**
    * The build encountered an unexpected error.
    */
   const STATUS_ERROR = 'error';
@@ -75,6 +80,8 @@
         return pht('Passed');
       case self::STATUS_FAILED:
         return pht('Failed');
+      case self::STATUS_ABORTED:
+        return pht('Aborted');
       case self::STATUS_ERROR:
         return pht('Unexpected Error');
       case self::STATUS_STOPPED:
@@ -97,6 +104,8 @@
         return PHUIStatusItemView::ICON_ACCEPT;
       case self::STATUS_FAILED:
         return PHUIStatusItemView::ICON_REJECT;
+      case self::STATUS_ABORTED:
+        return PHUIStatusItemView::ICON_MINUS;
       case self::STATUS_ERROR:
         return PHUIStatusItemView::ICON_MINUS;
       case self::STATUS_STOPPED:
@@ -118,6 +127,7 @@
       case self::STATUS_PASSED:
         return 'green';
       case self::STATUS_FAILED:
+      case self::STATUS_ABORTED:
       case self::STATUS_ERROR:
       case self::STATUS_DEADLOCKED:
         return 'red';
@@ -310,6 +320,7 @@
     switch ($this->getBuildStatus()) {
       case self::STATUS_PASSED:
       case self::STATUS_FAILED:
+      case self::STATUS_ABORTED:
       case self::STATUS_ERROR:
       case self::STATUS_STOPPED:
         return true;
@@ -345,6 +356,10 @@
            !$this->isStopping();
   }
 
+  public function canAbortBuild() {
+    return !$this->isComplete();
+  }
+
   public function canResumeBuild() {
     return $this->isStopped() &&
            !$this->isResuming();
@@ -362,6 +377,9 @@
         case HarbormasterBuildCommand::COMMAND_RESTART:
           $is_stopping = false;
           break;
+        case HarbormasterBuildCommand::COMMAND_ABORT:
+          $is_stopping = true;
+          break;
       }
     }
 
@@ -380,6 +398,9 @@
         case HarbormasterBuildCommand::COMMAND_STOP:
           $is_resuming = false;
           break;
+        case HarbormasterBuildCommand::COMMAND_ABORT:
+          $is_resuming = false;
+          break;
       }
     }
 
@@ -400,6 +421,20 @@
     return $is_restarting;
   }
 
+  public function isAborting() {
+    $is_aborting = false;
+    foreach ($this->getUnprocessedCommands() as $command_object) {
+      $command = $command_object->getCommand();
+      switch ($command) {
+        case HarbormasterBuildCommand::COMMAND_ABORT:
+          $is_aborting = true;
+          break;
+      }
+    }
+
+    return $is_aborting;
+  }
+
   public function deleteUnprocessedCommands() {
     foreach ($this->getUnprocessedCommands() as $key => $command_object) {
       $command_object->delete();
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuildTarget.php b/src/applications/harbormaster/storage/build/HarbormasterBuildTarget.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuildTarget.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuildTarget.php
@@ -220,6 +220,7 @@
   public function isFailed() {
     switch ($this->getTargetStatus()) {
       case self::STATUS_FAILED:
+      case self::STATUS_ABORTED:
         return true;
     }