diff --git a/src/applications/harbormaster/controller/HarbormasterPlanViewController.php b/src/applications/harbormaster/controller/HarbormasterPlanViewController.php
index c92de97c04..1ce17bf4f4 100644
--- a/src/applications/harbormaster/controller/HarbormasterPlanViewController.php
+++ b/src/applications/harbormaster/controller/HarbormasterPlanViewController.php
@@ -1,478 +1,479 @@
 <?php
 
 final class HarbormasterPlanViewController extends HarbormasterPlanController {
 
   private $id;
 
   public function willProcessRequest(array $data) {
     $this->id = $data['id'];
   }
 
   public function processRequest() {
     $request = $this->getRequest();
     $viewer = $request->getUser();
 
     $id = $this->id;
 
     $plan = id(new HarbormasterBuildPlanQuery())
       ->setViewer($viewer)
       ->withIDs(array($id))
       ->executeOne();
     if (!$plan) {
       return new Aphront404Response();
     }
 
     $xactions = id(new HarbormasterBuildPlanTransactionQuery())
       ->setViewer($viewer)
       ->withObjectPHIDs(array($plan->getPHID()))
       ->execute();
 
     $xaction_view = id(new PhabricatorApplicationTransactionView())
       ->setUser($viewer)
       ->setObjectPHID($plan->getPHID())
       ->setTransactions($xactions)
       ->setShouldTerminate(true);
 
     $title = pht('Plan %d', $id);
 
     $header = id(new PHUIHeaderView())
       ->setHeader($title)
       ->setUser($viewer)
       ->setPolicyObject($plan);
 
     $box = id(new PHUIObjectBoxView())
       ->setHeader($header);
 
     $actions = $this->buildActionList($plan);
     $this->buildPropertyLists($box, $plan, $actions);
 
     $crumbs = $this->buildApplicationCrumbs();
     $crumbs->addTextCrumb(pht('Plan %d', $id));
 
     list($step_list, $has_any_conflicts, $would_deadlock) =
       $this->buildStepList($plan);
 
     if ($would_deadlock) {
       $box->setFormErrors(
         array(
           pht(
             'This build plan will deadlock when executed, due to '.
             'circular dependencies present in the build plan. '.
             'Examine the step list and resolve the deadlock.'),
         ));
     } else if ($has_any_conflicts) {
       // A deadlocking build will also cause all the artifacts to be
       // invalid, so we just skip showing this message if that's the
       // case.
       $box->setFormErrors(
         array(
           pht(
             'This build plan has conflicts in one or more build steps. '.
             'Examine the step list and resolve the listed errors.'),
         ));
     }
 
     return $this->buildApplicationPage(
       array(
         $crumbs,
         $box,
         $step_list,
         $xaction_view,
       ),
       array(
         'title' => $title,
       ));
   }
 
   private function buildStepList(HarbormasterBuildPlan $plan) {
     $request = $this->getRequest();
     $viewer = $request->getUser();
 
     $run_order =
       HarbormasterBuildGraph::determineDependencyExecution($plan);
 
     $steps = id(new HarbormasterBuildStepQuery())
       ->setViewer($viewer)
       ->withBuildPlanPHIDs(array($plan->getPHID()))
       ->execute();
     $steps = mpull($steps, null, 'getPHID');
 
     $can_edit = $this->hasApplicationCapability(
       HarbormasterManagePlansCapability::CAPABILITY);
 
     $step_list = id(new PHUIObjectItemListView())
       ->setUser($viewer)
       ->setNoDataString(
         pht('This build plan does not have any build steps yet.'));
 
     $i = 1;
     $last_depth = 0;
     $has_any_conflicts = false;
     $is_deadlocking = false;
     foreach ($run_order as $run_ref) {
       $step = $steps[$run_ref['node']->getPHID()];
       $depth = $run_ref['depth'] + 1;
       if ($last_depth !== $depth) {
         $last_depth = $depth;
         $i = 1;
       } else {
         $i++;
       }
 
       $implementation = null;
       try {
         $implementation = $step->getStepImplementation();
       } catch (Exception $ex) {
         // We can't initialize the implementation. This might be because
         // it's been renamed or no longer exists.
         $item = id(new PHUIObjectItemView())
           ->setObjectName(pht('Step %d.%d', $depth, $i))
           ->setHeader(pht('Unknown Implementation'))
           ->setBarColor('red')
           ->addAttribute(pht(
             'This step has an invalid implementation (%s).',
             $step->getClassName()))
           ->addAction(
             id(new PHUIListItemView())
               ->setIcon('fa-times')
               ->addSigil('harbormaster-build-step-delete')
               ->setWorkflow(true)
               ->setRenderNameAsTooltip(true)
               ->setName(pht('Delete'))
               ->setHref(
                 $this->getApplicationURI('step/delete/'.$step->getID().'/')));
         $step_list->addItem($item);
         continue;
       }
       $item = id(new PHUIObjectItemView())
         ->setObjectName(pht('Step %d.%d', $depth, $i))
         ->setHeader($step->getName());
 
       $item->addAttribute($implementation->getDescription());
 
       $step_id = $step->getID();
       $edit_uri = $this->getApplicationURI("step/edit/{$step_id}/");
       $delete_uri = $this->getApplicationURI("step/delete/{$step_id}/");
 
       if ($can_edit) {
         $item->setHref($edit_uri);
       }
 
       $item
         ->setHref($edit_uri)
         ->addAction(
           id(new PHUIListItemView())
             ->setIcon('fa-times')
             ->addSigil('harbormaster-build-step-delete')
             ->setWorkflow(true)
             ->setDisabled(!$can_edit)
             ->setHref(
               $this->getApplicationURI('step/delete/'.$step->getID().'/')));
 
       $depends = $step->getStepImplementation()->getDependencies($step);
       $inputs = $step->getStepImplementation()->getArtifactInputs();
       $outputs = $step->getStepImplementation()->getArtifactOutputs();
 
       $has_conflicts = false;
       if ($depends || $inputs || $outputs) {
         $available_artifacts =
           HarbormasterBuildStepImplementation::getAvailableArtifacts(
             $plan,
             $step,
             null);
+        $available_artifacts = ipull($available_artifacts, 'type');
 
         list($depends_ui, $has_conflicts) = $this->buildDependsOnList(
             $depends,
             pht('Depends On'),
             $steps);
 
         list($inputs_ui, $has_conflicts) = $this->buildArtifactList(
             $inputs,
             'in',
             pht('Input Artifacts'),
             $available_artifacts);
 
         list($outputs_ui) = $this->buildArtifactList(
             $outputs,
             'out',
             pht('Output Artifacts'),
             array());
 
         $item->appendChild(
           phutil_tag(
             'div',
             array(
               'class' => 'harbormaster-artifact-io',
             ),
             array(
               $depends_ui,
               $inputs_ui,
               $outputs_ui,
             )));
       }
 
       if ($has_conflicts) {
         $has_any_conflicts = true;
         $item->setBarColor('red');
       }
 
       if ($run_ref['cycle']) {
         $is_deadlocking = true;
       }
 
       if ($is_deadlocking) {
         $item->setBarColor('red');
       }
 
       $step_list->addItem($item);
     }
 
     return array($step_list, $has_any_conflicts, $is_deadlocking);
   }
 
   private function buildActionList(HarbormasterBuildPlan $plan) {
     $request = $this->getRequest();
     $viewer = $request->getUser();
     $id = $plan->getID();
 
     $list = id(new PhabricatorActionListView())
       ->setUser($viewer)
       ->setObject($plan)
       ->setObjectURI($this->getApplicationURI("plan/{$id}/"));
 
     $can_edit = $this->hasApplicationCapability(
       HarbormasterManagePlansCapability::CAPABILITY);
 
     $list->addAction(
       id(new PhabricatorActionView())
         ->setName(pht('Edit Plan'))
         ->setHref($this->getApplicationURI("plan/edit/{$id}/"))
         ->setWorkflow(!$can_edit)
         ->setDisabled(!$can_edit)
         ->setIcon('fa-pencil'));
 
     if ($plan->isDisabled()) {
       $list->addAction(
         id(new PhabricatorActionView())
           ->setName(pht('Enable Plan'))
           ->setHref($this->getApplicationURI("plan/disable/{$id}/"))
           ->setWorkflow(true)
           ->setDisabled(!$can_edit)
           ->setIcon('fa-check'));
     } else {
       $list->addAction(
         id(new PhabricatorActionView())
           ->setName(pht('Disable Plan'))
           ->setHref($this->getApplicationURI("plan/disable/{$id}/"))
           ->setWorkflow(true)
           ->setDisabled(!$can_edit)
           ->setIcon('fa-ban'));
     }
 
     $list->addAction(
       id(new PhabricatorActionView())
         ->setName(pht('Add Build Step'))
         ->setHref($this->getApplicationURI("step/add/{$id}/"))
         ->setWorkflow(true)
         ->setDisabled(!$can_edit)
         ->setIcon('fa-plus'));
 
     $list->addAction(
       id(new PhabricatorActionView())
         ->setName(pht('Run Plan Manually'))
         ->setHref($this->getApplicationURI("plan/run/{$id}/"))
         ->setWorkflow(true)
         ->setDisabled(!$can_edit)
         ->setIcon('fa-play-circle'));
 
     return $list;
   }
 
   private function buildPropertyLists(
     PHUIObjectBoxView $box,
     HarbormasterBuildPlan $plan,
     PhabricatorActionListView $actions) {
     $request = $this->getRequest();
     $viewer = $request->getUser();
 
     $properties = id(new PHUIPropertyListView())
       ->setUser($viewer)
       ->setObject($plan)
       ->setActionList($actions);
     $box->addPropertyList($properties);
 
     $properties->addProperty(
       pht('Created'),
       phabricator_datetime($plan->getDateCreated(), $viewer));
 
   }
 
   private function buildArtifactList(
     array $artifacts,
     $kind,
     $name,
     array $available_artifacts) {
     $has_conflicts = false;
 
     if (!$artifacts) {
       return array(null, $has_conflicts);
     }
 
     $this->requireResource('harbormaster-css');
 
     $header = phutil_tag(
       'div',
       array(
         'class' => 'harbormaster-artifact-summary-header',
       ),
       $name);
 
     $is_input = ($kind == 'in');
 
     $list = new PHUIStatusListView();
     foreach ($artifacts as $artifact) {
       $error = null;
 
       $key = idx($artifact, 'key');
       if (!strlen($key)) {
         $bound = phutil_tag('em', array(), pht('(null)'));
         if ($is_input) {
           // This is an unbound input. For now, all inputs are always required.
           $icon = PHUIStatusItemView::ICON_WARNING;
           $color = 'red';
           $icon_label = pht('Required Input');
           $has_conflicts = true;
           $error = pht('This input is required, but not configured.');
         } else {
           // This is an unnamed output. Outputs do not necessarily need to be
           // named.
           $icon = PHUIStatusItemView::ICON_OPEN;
           $color = 'bluegrey';
           $icon_label = pht('Unused Output');
         }
       } else {
         $bound = phutil_tag('strong', array(), $key);
         if ($is_input) {
           if (isset($available_artifacts[$key])) {
             if ($available_artifacts[$key] == idx($artifact, 'type')) {
               $icon = PHUIStatusItemView::ICON_ACCEPT;
               $color = 'green';
               $icon_label = pht('Valid Input');
             } else {
               $icon = PHUIStatusItemView::ICON_WARNING;
               $color = 'red';
               $icon_label = pht('Bad Input Type');
               $has_conflicts = true;
               $error = pht(
                 'This input is bound to the wrong artifact type. It is bound '.
                 'to a "%s" artifact, but should be bound to a "%s" artifact.',
                 $available_artifacts[$key],
                 idx($artifact, 'type'));
             }
           } else {
             $icon = PHUIStatusItemView::ICON_QUESTION;
             $color = 'red';
             $icon_label = pht('Unknown Input');
             $has_conflicts = true;
             $error = pht(
               'This input is bound to an artifact ("%s") which does not exist '.
               'at this stage in the build process.',
               $key);
           }
         } else {
           $icon = PHUIStatusItemView::ICON_DOWN;
           $color = 'green';
           $icon_label = pht('Valid Output');
         }
       }
 
       if ($error) {
         $note = array(
           phutil_tag('strong', array(), pht('ERROR:')),
           ' ',
           $error);
       } else {
         $note = $bound;
       }
 
       $list->addItem(
         id(new PHUIStatusItemView())
           ->setIcon($icon, $color, $icon_label)
           ->setTarget($artifact['name'])
           ->setNote($note));
     }
 
     $ui = array(
       $header,
       $list,
     );
 
     return array($ui, $has_conflicts);
   }
 
   private function buildDependsOnList(
     array $step_phids,
     $name,
     array $steps) {
     $has_conflicts = false;
 
     if (count($step_phids) === 0) {
       return null;
     }
 
     $this->requireResource('harbormaster-css');
 
     $steps = mpull($steps, null, 'getPHID');
 
     $header = phutil_tag(
       'div',
       array(
         'class' => 'harbormaster-artifact-summary-header',
       ),
       $name);
 
     $list = new PHUIStatusListView();
     foreach ($step_phids as $step_phid) {
       $error = null;
 
       if (idx($steps, $step_phid) === null) {
         $icon = PHUIStatusItemView::ICON_WARNING;
         $color = 'red';
         $icon_label = pht('Missing Dependency');
         $has_conflicts = true;
         $error = pht(
           'This dependency specifies a build step which doesn\'t exist.');
       } else {
         $bound = phutil_tag(
           'strong',
           array(),
           idx($steps, $step_phid)->getName());
         $icon = PHUIStatusItemView::ICON_ACCEPT;
         $color = 'green';
         $icon_label = pht('Valid Input');
       }
 
       if ($error) {
         $note = array(
           phutil_tag('strong', array(), pht('ERROR:')),
           ' ',
           $error);
       } else {
         $note = $bound;
       }
 
       $list->addItem(
         id(new PHUIStatusItemView())
           ->setIcon($icon, $color, $icon_label)
           ->setTarget(pht('Build Step'))
           ->setNote($note));
     }
 
     $ui = array(
       $header,
       $list,
     );
 
     return array($ui, $has_conflicts);
   }
 }
diff --git a/src/applications/harbormaster/engine/HarbormasterBuildGraph.php b/src/applications/harbormaster/engine/HarbormasterBuildGraph.php
index 3691f4629b..a696a2b3d6 100644
--- a/src/applications/harbormaster/engine/HarbormasterBuildGraph.php
+++ b/src/applications/harbormaster/engine/HarbormasterBuildGraph.php
@@ -1,60 +1,61 @@
 <?php
 
 /**
  * Directed graph representing a build plan
  */
 final class HarbormasterBuildGraph extends AbstractDirectedGraph {
 
   private $stepMap;
 
   public static function determineDependencyExecution(
     HarbormasterBuildPlan $plan) {
 
     $steps = id(new HarbormasterBuildStepQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withBuildPlanPHIDs(array($plan->getPHID()))
       ->execute();
 
     $steps_by_phid = mpull($steps, null, 'getPHID');
     $step_phids = mpull($steps, 'getPHID');
 
     if (count($steps) === 0) {
       return array();
     }
 
     $graph = id(new HarbormasterBuildGraph($steps_by_phid))
       ->addNodes($step_phids);
 
     $raw_results =
       $graph->getBestEffortTopographicallySortedNodes();
 
     $results = array();
     foreach ($raw_results as $node) {
       $results[] = array(
         'node' => $steps_by_phid[$node['node']],
         'depth' => $node['depth'],
         'cycle' => $node['cycle']);
     }
 
     return $results;
   }
 
   public function __construct($step_map) {
     $this->stepMap = $step_map;
   }
 
   protected function loadEdges(array $nodes) {
     $map = array();
     foreach ($nodes as $node) {
-      $deps = $this->stepMap[$node]->getDetail('dependsOn', array());
+      $step = $this->stepMap[$node];
+      $deps = $step->getStepImplementation()->getDependencies($step);
 
       $map[$node] = array();
       foreach ($deps as $dep) {
         $map[$node][] = $dep;
       }
     }
 
     return $map;
   }
 
 }
diff --git a/src/applications/harbormaster/step/HarbormasterBuildStepImplementation.php b/src/applications/harbormaster/step/HarbormasterBuildStepImplementation.php
index a4e09f6123..433b11165c 100644
--- a/src/applications/harbormaster/step/HarbormasterBuildStepImplementation.php
+++ b/src/applications/harbormaster/step/HarbormasterBuildStepImplementation.php
@@ -1,205 +1,225 @@
 <?php
 
 abstract class HarbormasterBuildStepImplementation {
 
   public static function getImplementations() {
     return id(new PhutilSymbolLoader())
       ->setAncestorClass('HarbormasterBuildStepImplementation')
       ->loadObjects();
   }
 
   public static function getImplementation($class) {
     $base = idx(self::getImplementations(), $class);
 
     if ($base) {
       return (clone $base);
     }
 
     return null;
   }
 
   public static function requireImplementation($class) {
     if (!$class) {
       throw new Exception(pht('No implementation is specified!'));
     }
 
     $implementation = self::getImplementation($class);
     if (!$implementation) {
       throw new Exception(pht('No such implementation "%s" exists!', $class));
     }
 
     return $implementation;
   }
 
   /**
    * The name of the implementation.
    */
   abstract public function getName();
 
   /**
    * The generic description of the implementation.
    */
   public function getGenericDescription() {
     return '';
   }
 
   /**
    * The description of the implementation, based on the current settings.
    */
   public function getDescription() {
     return $this->getGenericDescription();
   }
 
   /**
    * Run the build target against the specified build.
    */
   abstract public function execute(
     HarbormasterBuild $build,
     HarbormasterBuildTarget $build_target);
 
   /**
    * Gets the settings for this build step.
    */
   public function getSettings() {
     return $this->settings;
   }
 
   public function getSetting($key, $default = null) {
     return idx($this->settings, $key, $default);
   }
 
   /**
    * Loads the settings for this build step implementation from a build
    * step or target.
    */
   public final function loadSettings($build_object) {
     $this->settings = $build_object->getDetails();
     return $this;
   }
 
   /**
    * Return the name of artifacts produced by this command.
    *
    * Something like:
    *
    *   return array(
    *     'some_name_input_by_user' => 'host');
    *
    * Future steps will calculate all available artifact mappings
    * before them and filter on the type.
    *
    * @return array The mappings of artifact names to their types.
    */
   public function getArtifactInputs() {
     return array();
   }
 
   public function getArtifactOutputs() {
     return array();
   }
 
   public function getDependencies(HarbormasterBuildStep $build_step) {
-    return $build_step->getDetail('dependsOn', array());
+    $dependencies = $build_step->getDetail('dependsOn', array());
+
+    $inputs = $build_step->getStepImplementation()->getArtifactInputs();
+    $inputs = ipull($inputs, null, 'key');
+
+    $artifacts = $this->getAvailableArtifacts(
+      $build_step->getBuildPlan(),
+      $build_step,
+      null);
+
+    foreach ($artifacts as $key => $type) {
+      if (!array_key_exists($key, $inputs)) {
+        unset($artifacts[$key]);
+      }
+    }
+
+    $artifact_steps = ipull($artifacts, 'step');
+    $artifact_steps = mpull($artifact_steps, 'getPHID');
+
+    $dependencies = array_merge($dependencies, $artifact_steps);
+
+    return $dependencies;
   }
 
   /**
    * Returns a list of all artifacts made available in the build plan.
    */
   public static function getAvailableArtifacts(
     HarbormasterBuildPlan $build_plan,
     $current_build_step,
     $artifact_type) {
 
     $steps = id(new HarbormasterBuildStepQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withBuildPlanPHIDs(array($build_plan->getPHID()))
       ->execute();
 
+    $artifacts = array();
+
     $artifact_arrays = array();
     foreach ($steps as $step) {
       if ($current_build_step !== null &&
         $step->getPHID() === $current_build_step->getPHID()) {
 
         continue;
       }
 
       $implementation = $step->getStepImplementation();
-      $artifact_arrays[] = $implementation->getArtifactOutputs();
-    }
-
-    $artifacts = array();
-    foreach ($artifact_arrays as $array) {
+      $array = $implementation->getArtifactOutputs();
       $array = ipull($array, 'type', 'key');
       foreach ($array as $name => $type) {
         if ($type !== $artifact_type && $artifact_type !== null) {
           continue;
         }
-        $artifacts[$name] = $type;
+        $artifacts[$name] = array('type' => $type, 'step' => $step);
       }
     }
+
     return $artifacts;
   }
 
   /**
    * Convert a user-provided string with variables in it, like:
    *
    *   ls ${dirname}
    *
    * ...into a string with variables merged into it safely:
    *
    *   ls 'dir with spaces'
    *
    * @param string Name of a `vxsprintf` function, like @{function:vcsprintf}.
    * @param string User-provided pattern string containing `${variables}`.
    * @param dict   List of available replacement variables.
    * @return string String with variables replaced safely into it.
    */
   protected function mergeVariables($function, $pattern, array $variables) {
     $regexp = '/\\$\\{(?P<name>[a-z\\.]+)\\}/';
 
     $matches = null;
     preg_match_all($regexp, $pattern, $matches);
 
     $argv = array();
     foreach ($matches['name'] as $name) {
       if (!array_key_exists($name, $variables)) {
         throw new Exception(pht("No such variable '%s'!", $name));
       }
       $argv[] = $variables[$name];
     }
 
     $pattern = str_replace('%', '%%', $pattern);
     $pattern = preg_replace($regexp, '%s', $pattern);
 
     return call_user_func($function, $pattern, $argv);
   }
 
   public function getFieldSpecifications() {
     return array();
   }
 
   protected function formatSettingForDescription($key, $default = null) {
     return $this->formatValueForDescription($this->getSetting($key, $default));
   }
 
   protected function formatValueForDescription($value) {
     if (strlen($value)) {
       return phutil_tag('strong', array(), $value);
     } else {
       return phutil_tag('em', array(), pht('(null)'));
     }
   }
 
   public function supportsWaitForMessage() {
     return false;
   }
 
   public function shouldWaitForMessage(HarbormasterBuildTarget $target) {
     if (!$this->supportsWaitForMessage()) {
       return false;
     }
 
     return (bool)$target->getDetail('builtin.wait-for-message');
   }
 
 }