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
@@ -2037,6 +2037,7 @@
     'PhabricatorRepositoryManagementMarkImportedWorkflow' => 'applications/repository/management/PhabricatorRepositoryManagementMarkImportedWorkflow.php',
     'PhabricatorRepositoryManagementMirrorWorkflow' => 'applications/repository/management/PhabricatorRepositoryManagementMirrorWorkflow.php',
     'PhabricatorRepositoryManagementParentsWorkflow' => 'applications/repository/management/PhabricatorRepositoryManagementParentsWorkflow.php',
+    'PhabricatorRepositoryManagementPruneWorkflow' => 'applications/repository/management/PhabricatorRepositoryManagementPruneWorkflow.php',
     'PhabricatorRepositoryManagementPullWorkflow' => 'applications/repository/management/PhabricatorRepositoryManagementPullWorkflow.php',
     'PhabricatorRepositoryManagementRefsWorkflow' => 'applications/repository/management/PhabricatorRepositoryManagementRefsWorkflow.php',
     'PhabricatorRepositoryManagementUpdateWorkflow' => 'applications/repository/management/PhabricatorRepositoryManagementUpdateWorkflow.php',
@@ -4907,6 +4908,7 @@
     'PhabricatorRepositoryManagementMarkImportedWorkflow' => 'PhabricatorRepositoryManagementWorkflow',
     'PhabricatorRepositoryManagementMirrorWorkflow' => 'PhabricatorRepositoryManagementWorkflow',
     'PhabricatorRepositoryManagementParentsWorkflow' => 'PhabricatorRepositoryManagementWorkflow',
+    'PhabricatorRepositoryManagementPruneWorkflow' => 'PhabricatorRepositoryManagementWorkflow',
     'PhabricatorRepositoryManagementPullWorkflow' => 'PhabricatorRepositoryManagementWorkflow',
     'PhabricatorRepositoryManagementRefsWorkflow' => 'PhabricatorRepositoryManagementWorkflow',
     'PhabricatorRepositoryManagementUpdateWorkflow' => 'PhabricatorRepositoryManagementWorkflow',
diff --git a/src/applications/repository/management/PhabricatorRepositoryManagementPruneWorkflow.php b/src/applications/repository/management/PhabricatorRepositoryManagementPruneWorkflow.php
new file mode 100644
--- /dev/null
+++ b/src/applications/repository/management/PhabricatorRepositoryManagementPruneWorkflow.php
@@ -0,0 +1,82 @@
+<?php
+
+final class PhabricatorRepositoryManagementPruneWorkflow
+  extends PhabricatorRepositoryManagementWorkflow {
+
+  public function didConstruct() {
+    $this
+      ->setName('prune')
+      ->setExamples('**prune** __repository__ ...')
+      ->setSynopsis('Prune __repository__, removing orphaned commits from repository named by callsign.')
+      ->setArguments(
+        array(
+          array(
+            'name'        => 'verbose',
+            'help'        => 'Show additional debugging information.',
+          ),
+          array(
+            'name'        => 'repos',
+            'wildcard'    => true,
+          ),
+        ));
+  }
+
+  public function execute(PhutilArgumentParser $args) {
+    $repos = $this->loadRepositories($args, 'repos');
+
+    if (!$repos) {
+      throw new PhutilArgumentUsageException(
+        'Specify one or more repositories to prune, by callsign.');
+    }
+
+    $console = PhutilConsole::getConsole();
+    foreach ($repos as $repo) {
+      $console->writeOut("Pruning '%s'...\n", $repo->getCallsign());
+
+      $commits = id(new DiffusionCommitQuery)
+        ->withRepository($repo)
+        ->setViewer(PhabricatorUser::getOmnipotentUser())
+        ->execute();
+      $bad_commits = array();
+
+      $console->writeOut("For each commit we have record of in phabricator, "
+        ."we will try to resolve it in the VCS. This will show errors for any "
+        ."that are missing.\n");
+
+      foreach ($commits as $commit) {
+        $out = $repo->execLocalCommand(
+          'show %s',
+          $commit->getCommitIdentifier());
+
+        if (array_shift($out) == 128) {
+          $console->writeOut(trim(implode($out,"\n"))."\n");
+          $bad_commits[] = $commit;
+        }
+      }
+
+      if (count($bad_commits) == 0) {
+        $console->writeOut("No orphaned commits.\n");
+        continue;
+      }
+
+      $ok = $console->confirm(
+        pht(
+          'Found %d orphaned commits out of %d total commits. Are you '
+          .'absolutely certain you want to destroy the commits listed above?',
+          new PhutilNumber(count($bad_commits)),
+          new PhutilNumber(count($commits))
+        ));
+      if (!$ok) {
+        throw new PhutilArgumentUsageException(
+          pht('Aborted, your commits are safe.'));
+      }
+
+      foreach ($bad_commits as $commit) {
+        $commit->delete();
+      }
+    }
+
+    return 0;
+  }
+
+}