diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -1443,6 +1443,7 @@
     'HarbormasterQueryBuildsConduitAPIMethod' => 'applications/harbormaster/conduit/HarbormasterQueryBuildsConduitAPIMethod.php',
     'HarbormasterQueryBuildsSearchEngineAttachment' => 'applications/harbormaster/engineextension/HarbormasterQueryBuildsSearchEngineAttachment.php',
     'HarbormasterRemarkupRule' => 'applications/harbormaster/remarkup/HarbormasterRemarkupRule.php',
+    'HarbormasterRestartException' => 'applications/harbormaster/exception/HarbormasterRestartException.php',
     'HarbormasterRunBuildPlansHeraldAction' => 'applications/harbormaster/herald/HarbormasterRunBuildPlansHeraldAction.php',
     'HarbormasterSchemaSpec' => 'applications/harbormaster/storage/HarbormasterSchemaSpec.php',
     'HarbormasterScratchTable' => 'applications/harbormaster/storage/HarbormasterScratchTable.php',
@@ -7093,6 +7094,7 @@
     'HarbormasterQueryBuildsConduitAPIMethod' => 'HarbormasterConduitAPIMethod',
     'HarbormasterQueryBuildsSearchEngineAttachment' => 'PhabricatorSearchEngineAttachment',
     'HarbormasterRemarkupRule' => 'PhabricatorObjectRemarkupRule',
+    'HarbormasterRestartException' => 'Exception',
     'HarbormasterRunBuildPlansHeraldAction' => 'HeraldAction',
     'HarbormasterSchemaSpec' => 'PhabricatorConfigSchemaSpec',
     'HarbormasterScratchTable' => 'HarbormasterDAO',
diff --git a/src/applications/harbormaster/constants/HarbormasterBuildStatus.php b/src/applications/harbormaster/constants/HarbormasterBuildStatus.php
--- a/src/applications/harbormaster/constants/HarbormasterBuildStatus.php
+++ b/src/applications/harbormaster/constants/HarbormasterBuildStatus.php
@@ -52,6 +52,10 @@
     return ($this->key === self::STATUS_PASSED);
   }
 
+  public function isFailed() {
+    return ($this->key === self::STATUS_FAILED);
+  }
+
 
   /**
    * Get a human readable name for a build status constant.
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
@@ -64,19 +64,13 @@
             'restart. Side effects of the build will occur again. Really '.
             'restart build?');
           $submit = pht('Restart Build');
-        } else if (!$build->getBuildPlan()->canRestartBuildPlan()) {
-          $title = pht('Not Restartable');
-          $body = pht(
-            'The build plan for this build is not restartable, so you '.
-            'can not restart the build.');
         } else {
-          $title = pht('Unable to Restart Build');
-          if ($build->isRestarting()) {
-            $body = pht(
-              'This build is already restarting. You can not reissue a '.
-              'restart command to a restarting build.');
-          } else {
-            $body = pht('You can not restart this build.');
+          try {
+            $build->assertCanRestartBuild();
+            throw new Exception(pht('Expected to be unable to restart build.'));
+          } catch (HarbormasterRestartException $ex) {
+            $title = $ex->getTitle();
+            $body = $ex->getBody();
           }
         }
         break;
diff --git a/src/applications/harbormaster/exception/HarbormasterRestartException.php b/src/applications/harbormaster/exception/HarbormasterRestartException.php
new file mode 100644
--- /dev/null
+++ b/src/applications/harbormaster/exception/HarbormasterRestartException.php
@@ -0,0 +1,33 @@
+<?php
+
+final class HarbormasterRestartException extends Exception {
+
+  private $title;
+  private $body = array();
+
+  public function __construct($title, $body = null) {
+    $this->setTitle($title);
+    $this->appendParagraph($body);
+
+    parent::__construct($title);
+  }
+
+  public function setTitle($title) {
+    $this->title = $title;
+    return $this;
+  }
+
+  public function getTitle() {
+    return $this->title;
+  }
+
+  public function appendParagraph($description) {
+    $this->body[] = $description;
+    return $this;
+  }
+
+  public function getBody() {
+    return $this->body;
+  }
+
+}
diff --git a/src/applications/harbormaster/plan/HarbormasterBuildPlanBehavior.php b/src/applications/harbormaster/plan/HarbormasterBuildPlanBehavior.php
--- a/src/applications/harbormaster/plan/HarbormasterBuildPlanBehavior.php
+++ b/src/applications/harbormaster/plan/HarbormasterBuildPlanBehavior.php
@@ -15,6 +15,7 @@
 
   const BEHAVIOR_RESTARTABLE = 'restartable';
   const RESTARTABLE_ALWAYS = 'always';
+  const RESTARTABLE_IF_FAILED = 'failed';
   const RESTARTABLE_NEVER = 'never';
 
   const BEHAVIOR_DRAFTS = 'hold-drafts';
@@ -251,6 +252,12 @@
         ->setIsDefault(true)
         ->setDescription(
           pht('The build may be restarted.')),
+      id(new HarbormasterBuildPlanBehaviorOption())
+        ->setKey(self::RESTARTABLE_IF_FAILED)
+        ->setIcon('fa-times-circle-o yellow')
+        ->setName(pht('If Failed'))
+        ->setDescription(
+          pht('The build may be restarted if it has failed.')),
       id(new HarbormasterBuildPlanBehaviorOption())
         ->setKey(self::RESTARTABLE_NEVER)
         ->setIcon('fa-times 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
@@ -183,6 +183,10 @@
     return $this->getBuildStatusObject()->isPassed();
   }
 
+  public function isFailed() {
+    return $this->getBuildStatusObject()->isFailed();
+  }
+
   public function getURI() {
     $id = $this->getID();
     return "/harbormaster/build/{$id}/";
@@ -211,16 +215,60 @@
   }
 
   public function canRestartBuild() {
-    if ($this->isAutobuild()) {
+    try {
+      $this->assertCanRestartBuild();
+      return true;
+    } catch (HarbormasterRestartException $ex) {
       return false;
     }
+  }
+
+  public function assertCanRestartBuild() {
+    if ($this->isAutobuild()) {
+      throw new HarbormasterRestartException(
+        pht('Can Not Restart Autobuild'),
+        pht(
+          'This build can not be restarted because it is an automatic '.
+          'build.'));
+    }
 
+    $restartable = HarbormasterBuildPlanBehavior::BEHAVIOR_RESTARTABLE;
     $plan = $this->getBuildPlan();
-    if (!$plan->canRestartBuildPlan()) {
-      return false;
+
+    $option = HarbormasterBuildPlanBehavior::getBehavior($restartable)
+      ->getPlanOption($plan);
+    $option_key = $option->getKey();
+
+    $never_restartable = HarbormasterBuildPlanBehavior::RESTARTABLE_NEVER;
+    $is_never = ($option_key === $never_restartable);
+    if ($is_never) {
+      throw new HarbormasterRestartException(
+        pht('Build Plan Prevents Restart'),
+        pht(
+          'This build can not be restarted because the build plan is '.
+          'configured to prevent the build from restarting.'));
+    }
+
+    $failed_restartable = HarbormasterBuildPlanBehavior::RESTARTABLE_IF_FAILED;
+    $is_failed = ($option_key === $failed_restartable);
+    if ($is_failed) {
+      if (!$this->isFailed()) {
+        throw new HarbormasterRestartException(
+          pht('Only Restartable if Failed'),
+          pht(
+            'This build can not be restarted because the build plan is '.
+            'configured to prevent the build from restarting unless it '.
+            'has failed, and it has not failed.'));
+      }
     }
 
-    return !$this->isRestarting();
+    if ($this->isRestarting()) {
+      throw new HarbormasterRestartException(
+        pht('Already Restarting'),
+        pht(
+          'This build is already restarting. You can not reissue a restart '.
+          'command to a restarting build.'));
+    }
   }
 
   public function canPauseBuild() {
diff --git a/src/applications/harbormaster/storage/configuration/HarbormasterBuildPlan.php b/src/applications/harbormaster/storage/configuration/HarbormasterBuildPlan.php
--- a/src/applications/harbormaster/storage/configuration/HarbormasterBuildPlan.php
+++ b/src/applications/harbormaster/storage/configuration/HarbormasterBuildPlan.php
@@ -175,16 +175,6 @@
       $capability);
   }
 
-  public function canRestartBuildPlan() {
-    $restartable = HarbormasterBuildPlanBehavior::BEHAVIOR_RESTARTABLE;
-    $is_restartable = HarbormasterBuildPlanBehavior::RESTARTABLE_ALWAYS;
-
-    $option = HarbormasterBuildPlanBehavior::getBehavior($restartable)
-      ->getPlanOption($this);
-
-    return ($option->getKey() === $is_restartable);
-  }
-
 
 /* -(  PhabricatorSubscribableInterface  )----------------------------------- */