Index: src/applications/harbormaster/step/HarbormasterRunBuildPlanBuildImplementation.php
===================================================================
--- src/applications/harbormaster/step/HarbormasterRunBuildPlanBuildImplementation.php
+++ src/applications/harbormaster/step/HarbormasterRunBuildPlanBuildImplementation.php
@@ -91,6 +91,16 @@
       return;
     }
 
+    if ($target_plan->isDisabled()) {
+      $log_disabled = $build->createLog($build_target, 'plan', 'disabled');
+      $start_disabled = $log_disabled->start();
+      $log_disabled->append(
+        'The target build plan is disabled.  This target will return '.
+        'successful, but the target build will not have run.');
+      $log_disabled->finalize($start_disabled);
+      return;
+    }
+
     // Find all other builds running on this buildable.
     $buildable = $build->getBuildable();
     $other_builds = id(new HarbormasterBuildQuery())