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
@@ -6525,6 +6525,7 @@
       'PhabricatorApplicationTransactionInterface',
       'PhabricatorPolicyInterface',
       'PhabricatorConduitResultInterface',
+      'PhabricatorDestructibleInterface',
     ),
     'HarbormasterBuildAbortedException' => 'Exception',
     'HarbormasterBuildActionController' => 'HarbormasterController',
@@ -6532,6 +6533,7 @@
     'HarbormasterBuildArtifact' => array(
       'HarbormasterDAO',
       'PhabricatorPolicyInterface',
+      'PhabricatorDestructibleInterface',
     ),
     'HarbormasterBuildArtifactPHIDType' => 'PhabricatorPHIDType',
     'HarbormasterBuildArtifactQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
@@ -6564,6 +6566,7 @@
     'HarbormasterBuildMessage' => array(
       'HarbormasterDAO',
       'PhabricatorPolicyInterface',
+      'PhabricatorDestructibleInterface',
     ),
     'HarbormasterBuildMessageQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'HarbormasterBuildPHIDType' => 'PhabricatorPHIDType',
@@ -6614,6 +6617,7 @@
     'HarbormasterBuildTarget' => array(
       'HarbormasterDAO',
       'PhabricatorPolicyInterface',
+      'PhabricatorDestructibleInterface',
     ),
     'HarbormasterBuildTargetPHIDType' => 'PhabricatorPHIDType',
     'HarbormasterBuildTargetQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
@@ -6628,6 +6632,7 @@
       'PhabricatorApplicationTransactionInterface',
       'PhabricatorPolicyInterface',
       'HarbormasterBuildableInterface',
+      'PhabricatorDestructibleInterface',
     ),
     'HarbormasterBuildableActionController' => 'HarbormasterController',
     'HarbormasterBuildableListController' => 'HarbormasterController',
diff --git a/src/applications/harbormaster/storage/HarbormasterBuildMessage.php b/src/applications/harbormaster/storage/HarbormasterBuildMessage.php
--- a/src/applications/harbormaster/storage/HarbormasterBuildMessage.php
+++ b/src/applications/harbormaster/storage/HarbormasterBuildMessage.php
@@ -6,8 +6,11 @@
  * conditions where we receive a message before a build plan is ready to
  * accept it.
  */
-final class HarbormasterBuildMessage extends HarbormasterDAO
-  implements PhabricatorPolicyInterface {
+final class HarbormasterBuildMessage
+  extends HarbormasterDAO
+  implements
+    PhabricatorPolicyInterface,
+    PhabricatorDestructibleInterface {
 
   protected $authorPHID;
   protected $receiverPHID;
@@ -74,4 +77,13 @@
     return pht('Build messages have the same policies as their receivers.');
   }
 
+
+/* -(  PhabricatorDestructibleInterface  )----------------------------------- */
+
+
+  public function destroyObjectPermanently(
+    PhabricatorDestructionEngine $engine) {
+    $this->delete();
+  }
+
 }
diff --git a/src/applications/harbormaster/storage/HarbormasterBuildable.php b/src/applications/harbormaster/storage/HarbormasterBuildable.php
--- a/src/applications/harbormaster/storage/HarbormasterBuildable.php
+++ b/src/applications/harbormaster/storage/HarbormasterBuildable.php
@@ -1,10 +1,12 @@
 <?php
 
-final class HarbormasterBuildable extends HarbormasterDAO
+final class HarbormasterBuildable
+  extends HarbormasterDAO
   implements
     PhabricatorApplicationTransactionInterface,
     PhabricatorPolicyInterface,
-    HarbormasterBuildableInterface {
+    HarbormasterBuildableInterface,
+    PhabricatorDestructibleInterface {
 
   protected $buildablePHID;
   protected $containerPHID;
@@ -340,4 +342,32 @@
   }
 
 
+/* -(  PhabricatorDestructibleInterface  )----------------------------------- */
+
+
+  public function destroyObjectPermanently(
+    PhabricatorDestructionEngine $engine) {
+    $viewer = $engine->getViewer();
+
+    $this->openTransaction();
+      $builds = id(new HarbormasterBuildQuery())
+        ->setViewer($viewer)
+        ->withBuildablePHIDs(array($this->getPHID()))
+        ->execute();
+      foreach ($builds as $build) {
+        $engine->destroyObject($build);
+      }
+
+      $messages = id(new HarbormasterBuildMessageQuery())
+        ->setViewer($viewer)
+        ->withReceiverPHIDs(array($this->getPHID()))
+        ->execute();
+      foreach ($messages as $message) {
+        $engine->destroyObject($message);
+      }
+
+      $this->delete();
+    $this->saveTransaction();
+  }
+
 }
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
@@ -4,7 +4,8 @@
   implements
     PhabricatorApplicationTransactionInterface,
     PhabricatorPolicyInterface,
-    PhabricatorConduitResultInterface {
+    PhabricatorConduitResultInterface,
+    PhabricatorDestructibleInterface {
 
   protected $buildablePHID;
   protected $buildPlanPHID;
@@ -455,4 +456,33 @@
     );
   }
 
+
+/* -(  PhabricatorDestructibleInterface  )----------------------------------- */
+
+  public function destroyObjectPermanently(
+    PhabricatorDestructionEngine $engine) {
+    $viewer = $engine->getViewer();
+
+    $this->openTransaction();
+      $targets = id(new HarbormasterBuildTargetQuery())
+        ->setViewer($viewer)
+        ->withBuildPHIDs(array($this->getPHID()))
+        ->execute();
+      foreach ($targets as $target) {
+        $engine->destroyObject($target);
+      }
+
+      $messages = id(new HarbormasterBuildMessageQuery())
+        ->setViewer($viewer)
+        ->withReceiverPHIDs(array($this->getPHID()))
+        ->execute();
+      foreach ($messages as $message) {
+        $engine->destroyObject($message);
+      }
+
+      $this->delete();
+    $this->saveTransaction();
+  }
+
+
 }
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php b/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuildArtifact.php
@@ -1,7 +1,10 @@
 <?php
 
-final class HarbormasterBuildArtifact extends HarbormasterDAO
-  implements PhabricatorPolicyInterface {
+final class HarbormasterBuildArtifact
+  extends HarbormasterDAO
+  implements
+    PhabricatorPolicyInterface,
+    PhabricatorDestructibleInterface {
 
   protected $buildTargetPHID;
   protected $artifactType;
@@ -147,4 +150,19 @@
     return pht('Users must be able to see a buildable to see its artifacts.');
   }
 
+
+/* -(  PhabricatorDestructibleInterface  )----------------------------------- */
+
+
+  public function destroyObjectPermanently(
+    PhabricatorDestructionEngine $engine) {
+
+    $viewer = $this->getViewer();
+
+    $this->openTransaction();
+      $this->releaseArtifact($viewer);
+      $this->delete();
+    $this->saveTransaction();
+  }
+
 }
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
@@ -1,7 +1,10 @@
 <?php
 
-final class HarbormasterBuildTarget extends HarbormasterDAO
-  implements PhabricatorPolicyInterface {
+final class HarbormasterBuildTarget
+  extends HarbormasterDAO
+  implements
+    PhabricatorPolicyInterface,
+    PhabricatorDestructibleInterface {
 
   protected $name;
   protected $buildPHID;
@@ -354,4 +357,59 @@
     return pht('Users must be able to see a build to view its build targets.');
   }
 
+
+/* -(  PhabricatorDestructibleInterface  )----------------------------------- */
+
+
+  public function destroyObjectPermanently(
+    PhabricatorDestructionEngine $engine) {
+    $viewer = $engine->getViewer();
+
+    $this->openTransaction();
+
+      $lint_message = new HarbormasterBuildLintMessage();
+      $conn = $lint_message->establishConnection('w');
+      queryfx(
+        $conn,
+        'DELETE FROM %T WHERE buildTargetPHID = %s',
+        $lint_message->getTableName(),
+        $this->getPHID());
+
+      $unit_message = new HarbormasterBuildUnitMessage();
+      $conn = $unit_message->establishConnection('w');
+      queryfx(
+        $conn,
+        'DELETE FROM %T WHERE buildTargetPHID = %s',
+        $unit_message->getTableName(),
+        $this->getPHID());
+
+      $logs = id(new HarbormasterBuildLogQuery())
+        ->setViewer($viewer)
+        ->withBuildTargetPHIDs(array($this->getPHID()))
+        ->execute();
+      foreach ($logs as $log) {
+        $engine->destroyObject($log);
+      }
+
+      $artifacts = id(new HarbormasterBuildArtifactQuery())
+        ->setViewer($viewer)
+        ->withBuildTargetPHIDs(array($this->getPHID()))
+        ->execute();
+      foreach ($artifacts as $artifact) {
+        $engine->destroyObject($artifact);
+      }
+
+      $messages = id(new HarbormasterBuildMessageQuery())
+        ->setViewer($viewer)
+        ->withReceiverPHIDs(array($this->getPHID()))
+        ->execute();
+      foreach ($messages as $message) {
+        $engine->destroyObject($message);
+      }
+
+      $this->delete();
+    $this->saveTransaction();
+  }
+
+
 }