diff --git a/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php b/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
--- a/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
+++ b/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
@@ -493,6 +493,90 @@
     $this->assertFalse((bool)$this->refreshProject($child, $user2));
   }
 
+  public function testSlugMaps() {
+    // When querying by slugs, slugs should be normalized and the mapping
+    // should be reported correctly.
+    $user = $this->createUser();
+    $user->save();
+
+    $name = 'queryslugproject';
+    $name2 = 'QUERYslugPROJECT';
+    $slug = 'queryslugextra';
+    $slug2 = 'QuErYSlUgExTrA';
+
+    $project = PhabricatorProject::initializeNewProject($user);
+
+    $xactions = array();
+
+    $xactions[] = id(new PhabricatorProjectTransaction())
+      ->setTransactionType(PhabricatorProjectTransaction::TYPE_NAME)
+      ->setNewValue($name);
+
+    $xactions[] = id(new PhabricatorProjectTransaction())
+      ->setTransactionType(PhabricatorProjectTransaction::TYPE_SLUGS)
+      ->setNewValue(array($slug));
+
+    $this->applyTransactions($project, $user, $xactions);
+
+    $project_query = id(new PhabricatorProjectQuery())
+      ->setViewer($user)
+      ->withSlugs(array($name));
+    $project_query->execute();
+    $map = $project_query->getSlugMap();
+
+    $this->assertEqual(
+      array(
+        $name => $project->getPHID(),
+      ),
+      ipull($map, 'projectPHID'));
+
+    $project_query = id(new PhabricatorProjectQuery())
+      ->setViewer($user)
+      ->withSlugs(array($slug));
+    $project_query->execute();
+    $map = $project_query->getSlugMap();
+
+    $this->assertEqual(
+      array(
+        $slug => $project->getPHID(),
+      ),
+      ipull($map, 'projectPHID'));
+
+    $project_query = id(new PhabricatorProjectQuery())
+      ->setViewer($user)
+      ->withSlugs(array($name, $slug, $name2, $slug2));
+    $project_query->execute();
+    $map = $project_query->getSlugMap();
+
+    $expect = array(
+      $name => $project->getPHID(),
+      $slug => $project->getPHID(),
+      $name2 => $project->getPHID(),
+      $slug2 => $project->getPHID(),
+    );
+
+    $actual = ipull($map, 'projectPHID');
+
+    ksort($expect);
+    ksort($actual);
+
+    $this->assertEqual($expect, $actual);
+
+    $expect = array(
+      $name => $name,
+      $slug => $slug,
+      $name2 => $name,
+      $slug2 => $slug,
+    );
+
+    $actual = ipull($map, 'slug');
+
+    ksort($expect);
+    ksort($actual);
+
+    $this->assertEqual($expect, $actual);
+  }
+
   private function attemptProjectEdit(
     PhabricatorProject $proj,
     PhabricatorUser $user,
diff --git a/src/applications/project/query/PhabricatorProjectQuery.php b/src/applications/project/query/PhabricatorProjectQuery.php
--- a/src/applications/project/query/PhabricatorProjectQuery.php
+++ b/src/applications/project/query/PhabricatorProjectQuery.php
@@ -7,6 +7,8 @@
   private $phids;
   private $memberPHIDs;
   private $slugs;
+  private $slugNormals;
+  private $slugMap;
   private $names;
   private $nameTokens;
   private $icons;
@@ -157,6 +159,24 @@
     );
   }
 
+  public function getSlugMap() {
+    if ($this->slugMap === null) {
+      throw new PhutilInvalidStateException('execute');
+    }
+    return $this->slugMap;
+  }
+
+  protected function willExecute() {
+    $this->slugMap = array();
+    $this->slugNormals = array();
+    if ($this->slugs) {
+      foreach ($this->slugs as $slug) {
+        $normal = PhabricatorSlug::normalizeProjectSlug($slug);
+        $this->slugNormals[$slug] = $normal;
+      }
+    }
+  }
+
   protected function loadPage() {
     return $this->loadStandardPage($this->newResultObject());
   }
@@ -287,17 +307,7 @@
       }
     }
 
-    if ($this->needSlugs) {
-      $slugs = id(new PhabricatorProjectSlug())
-        ->loadAllWhere(
-          'projectPHID IN (%Ls)',
-          mpull($projects, 'getPHID'));
-      $slugs = mgroup($slugs, 'getProjectPHID');
-      foreach ($projects as $project) {
-        $project_slugs = idx($slugs, $project->getPHID(), array());
-        $project->attachSlugs($project_slugs);
-      }
-    }
+    $this->loadSlugs($projects);
 
     return $projects;
   }
@@ -356,7 +366,7 @@
       $where[] = qsprintf(
         $conn,
         'slug.slug IN (%Ls)',
-        $this->slugs);
+        $this->slugNormals);
     }
 
     if ($this->names !== null) {
@@ -583,4 +593,76 @@
     return $ancestors;
   }
 
+  private function loadSlugs(array $projects) {
+    // Build a map from primary slugs to projects.
+    $primary_map = array();
+    foreach ($projects as $project) {
+      $primary_slug = $project->getPrimarySlug();
+      if ($primary_slug === null) {
+        continue;
+      }
+
+      $primary_map[$primary_slug] = $project;
+    }
+
+    // Link up all of the queried slugs which correspond to primary
+    // slugs. If we can link up everything from this (no slugs were queried,
+    // or only primary slugs were queried) we don't need to load anything
+    // else.
+    $unknown = $this->slugNormals;
+    foreach ($unknown as $input => $normal) {
+      if (!isset($primary_map[$normal])) {
+        continue;
+      }
+
+      $this->slugMap[$input] = array(
+        'slug' => $normal,
+        'projectPHID' => $primary_map[$normal]->getPHID(),
+      );
+
+      unset($unknown[$input]);
+    }
+
+    // If we need slugs, we have to load everything.
+    // If we still have some queried slugs which we haven't mapped, we only
+    // need to look for them.
+    // If we've mapped everything, we don't have to do any work.
+    $project_phids = mpull($projects, 'getPHID');
+    if ($this->needSlugs) {
+      $slugs = id(new PhabricatorProjectSlug())->loadAllWhere(
+        'projectPHID IN (%Ls)',
+        $project_phids);
+    } else if ($unknown) {
+      $slugs = id(new PhabricatorProjectSlug())->loadAllWhere(
+        'projectPHID IN (%Ls) AND slug IN (%Ls)',
+        $project_phids,
+        $unknown);
+    } else {
+      $slugs = array();
+    }
+
+    // Link up any slugs we were not able to link up earlier.
+    $extra_map = mpull($slugs, 'getProjectPHID', 'getSlug');
+    foreach ($unknown as $input => $normal) {
+      if (!isset($extra_map[$normal])) {
+        continue;
+      }
+
+      $this->slugMap[$input] = array(
+        'slug' => $normal,
+        'projectPHID' => $extra_map[$normal],
+      );
+
+      unset($unknown[$input]);
+    }
+
+    if ($this->needSlugs) {
+      $slug_groups = mgroup($slugs, 'getProjectPHID');
+      foreach ($projects as $project) {
+        $project_slugs = idx($slug_groups, $project->getPHID(), array());
+        $project->attachSlugs($project_slugs);
+      }
+    }
+  }
+
 }