diff --git a/src/applications/people/query/PhabricatorPeopleQuery.php b/src/applications/people/query/PhabricatorPeopleQuery.php
--- a/src/applications/people/query/PhabricatorPeopleQuery.php
+++ b/src/applications/people/query/PhabricatorPeopleQuery.php
@@ -17,6 +17,7 @@
   private $isApproved;
   private $nameLike;
   private $nameTokens;
+  private $namePrefixes;
 
   private $needPrimaryEmail;
   private $needProfile;
@@ -95,6 +96,11 @@
     return $this;
   }
 
+  public function withNamePrefixes(array $prefixes) {
+    $this->namePrefixes = $prefixes;
+    return $this;
+  }
+
   public function needPrimaryEmail($need) {
     $this->needPrimaryEmail = $need;
     return $this;
@@ -256,6 +262,17 @@
         $this->usernames);
     }
 
+    if ($this->namePrefixes) {
+      $parts = array();
+      foreach ($this->namePrefixes as $name_prefix) {
+        $parts[] = qsprintf(
+          $conn,
+          'user.username LIKE %>',
+          $name_prefix);
+      }
+      $where[] = '('.implode(' OR ', $parts).')';
+    }
+
     if ($this->emails !== null) {
       $where[] = qsprintf(
         $conn,
diff --git a/src/applications/people/typeahead/PhabricatorPeopleDatasource.php b/src/applications/people/typeahead/PhabricatorPeopleDatasource.php
--- a/src/applications/people/typeahead/PhabricatorPeopleDatasource.php
+++ b/src/applications/people/typeahead/PhabricatorPeopleDatasource.php
@@ -17,13 +17,18 @@
 
   public function loadResults() {
     $viewer = $this->getViewer();
-    $tokens = $this->getTokens();
 
     $query = id(new PhabricatorPeopleQuery())
       ->setOrderVector(array('username'));
 
-    if ($tokens) {
-      $query->withNameTokens($tokens);
+    if ($this->getPhase() == self::PHASE_PREFIX) {
+      $prefix = $this->getPrefixQuery();
+      $query->withNamePrefixes(array($prefix));
+    } else {
+      $tokens = $this->getTokens();
+      if ($tokens) {
+        $query->withNameTokens($tokens);
+      }
     }
 
     $users = $this->executeQuery($query);
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
@@ -12,6 +12,7 @@
   private $slugMap;
   private $allSlugs;
   private $names;
+  private $namePrefixes;
   private $nameTokens;
   private $icons;
   private $colors;
@@ -78,6 +79,11 @@
     return $this;
   }
 
+  public function withNamePrefixes(array $prefixes) {
+    $this->namePrefixes = $prefixes;
+    return $this;
+  }
+
   public function withNameTokens(array $tokens) {
     $this->nameTokens = array_values($tokens);
     return $this;
@@ -464,6 +470,17 @@
         $this->names);
     }
 
+    if ($this->namePrefixes) {
+      $parts = array();
+      foreach ($this->namePrefixes as $name_prefix) {
+        $parts[] = qsprintf(
+          $conn,
+          'name LIKE %>',
+          $name_prefix);
+      }
+      $where[] = '('.implode(' OR ', $parts).')';
+    }
+
     if ($this->icons !== null) {
       $where[] = qsprintf(
         $conn,
diff --git a/src/applications/project/typeahead/PhabricatorProjectDatasource.php b/src/applications/project/typeahead/PhabricatorProjectDatasource.php
--- a/src/applications/project/typeahead/PhabricatorProjectDatasource.php
+++ b/src/applications/project/typeahead/PhabricatorProjectDatasource.php
@@ -28,7 +28,10 @@
       ->needImages(true)
       ->needSlugs(true);
 
-    if ($tokens) {
+    if ($this->getPhase() == self::PHASE_PREFIX) {
+      $prefix = $this->getPrefixQuery();
+      $query->withNamePrefixes(array($prefix));
+    } else if ($tokens) {
       $query->withNameTokens($tokens);
     }
 
diff --git a/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php b/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
--- a/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
+++ b/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
@@ -325,6 +325,11 @@
         pht('Icon'),
         pht('Closed'),
         pht('Sprite'),
+        pht('Color'),
+        pht('Type'),
+        pht('Unique'),
+        pht('Auto'),
+        pht('Phase'),
       ));
 
     $result_box = id(new PHUIObjectBoxView())
diff --git a/src/applications/typeahead/datasource/PhabricatorTypeaheadCompositeDatasource.php b/src/applications/typeahead/datasource/PhabricatorTypeaheadCompositeDatasource.php
--- a/src/applications/typeahead/datasource/PhabricatorTypeaheadCompositeDatasource.php
+++ b/src/applications/typeahead/datasource/PhabricatorTypeaheadCompositeDatasource.php
@@ -4,6 +4,8 @@
   extends PhabricatorTypeaheadDatasource {
 
   private $usable;
+  private $prefixString;
+  private $prefixLength;
 
   abstract public function getComponentDatasources();
 
@@ -22,9 +24,51 @@
   }
 
   public function loadResults() {
+    $phases = array();
+
+    // We only need to do a prefix phase query if there's an actual query
+    // string. If the user didn't type anything, nothing can possibly match it.
+    if (strlen($this->getRawQuery())) {
+      $phases[] = self::PHASE_PREFIX;
+    }
+
+    $phases[] = self::PHASE_CONTENT;
+
     $offset = $this->getOffset();
     $limit = $this->getLimit();
 
+    $results = array();
+    foreach ($phases as $phase) {
+      if ($limit) {
+        $phase_limit = ($offset + $limit) - count($results);
+      } else {
+        $phase_limit = 0;
+      }
+
+      $phase_results = $this->loadResultsForPhase(
+        $phase,
+        $phase_limit);
+
+      foreach ($phase_results as $result) {
+        $results[] = $result;
+      }
+
+      if ($limit) {
+        if (count($results) >= $offset + $limit) {
+          break;
+        }
+      }
+    }
+
+    return $results;
+  }
+
+  protected function loadResultsForPhase($phase, $limit) {
+    if ($phase == self::PHASE_PREFIX) {
+      $this->prefixString = $this->getPrefixQuery();
+      $this->prefixLength = strlen($this->prefixString);
+    }
+
     // If the input query is a function like `members(platy`, and we can
     // parse the function, we strip the function off and hand the stripped
     // query to child sources. This makes it easier to implement function
@@ -62,28 +106,110 @@
       }
 
       $source
+        ->setPhase($phase)
         ->setFunctionStack($source_stack)
         ->setRawQuery($source_query)
         ->setQuery($this->getQuery())
         ->setViewer($this->getViewer());
 
-      if ($limit) {
-        $source->setLimit($offset + $limit);
-      }
-
       if ($is_browse) {
         $source->setIsBrowse(true);
       }
 
-      $source_results = $source->loadResults();
-      $source_results = $source->didLoadResults($source_results);
+      if ($limit) {
+        // If we are loading results from a source with a limit, it may return
+        // some results which belong to the wrong phase. We need an entire page
+        // of valid results in the correct phase AFTER any results for the
+        // wrong phase are filtered for pagination to work correctly.
+
+        // To make sure we can get there, we fetch more and more results until
+        // enough of them survive filtering to generate a full page.
+
+        // We start by fetching 150% of the results than we think we need, and
+        // double the amount we overfetch by each time.
+        $factor = 1.5;
+        while (true) {
+          $query_source = clone $source;
+          $total = (int)ceil($limit * $factor) + 1;
+          $query_source->setLimit($total);
+
+          $source_results = $query_source->loadResultsForPhase(
+            $phase,
+            $limit);
+
+          // If there are fewer unfiltered results than we asked for, we know
+          // this is the entire result set and we don't need to keep going.
+          if (count($source_results) < $total) {
+            $source_results = $query_source->didLoadResults($source_results);
+            $source_results = $this->filterPhaseResults(
+              $phase,
+              $source_results);
+            break;
+          }
+
+          // Otherwise, this result set have everything we need, or may not.
+          // Filter the results that are part of the wrong phase out first...
+          $source_results = $query_source->didLoadResults($source_results);
+          $source_results = $this->filterPhaseResults($phase, $source_results);
+
+          // Now check if we have enough results left. If we do, we're all set.
+          if (count($source_results) >= $total) {
+            break;
+          }
+
+          // We filtered out too many results to have a full page left, so we
+          // need to run the query again, asking for even more results. We'll
+          // keep doing this until we get a full page or get all of the
+          // results.
+          $factor = $factor * 2;
+        }
+      } else {
+        $source_results = $source->loadResults();
+        $source_results = $source->didLoadResults($source_results);
+        $source_results = $this->filterPhaseResults($phase, $source_results);
+      }
+
       $results[] = $source_results;
     }
 
     $results = array_mergev($results);
     $results = msort($results, 'getSortKey');
 
-    $count = count($results);
+    $results = $this->sliceResults($results);
+
+    return $results;
+  }
+
+  private function filterPhaseResults($phase, $source_results) {
+    foreach ($source_results as $key => $source_result) {
+      $result_phase = $this->getResultPhase($source_result);
+
+      if ($result_phase != $phase) {
+        unset($source_results[$key]);
+        continue;
+      }
+
+      $source_result->setPhase($result_phase);
+    }
+
+    return $source_results;
+  }
+
+  private function getResultPhase(PhabricatorTypeaheadResult $result) {
+    if ($this->prefixLength) {
+      $result_name = phutil_utf8_strtolower($result->getName());
+      if (!strncmp($result_name, $this->prefixString, $this->prefixLength)) {
+        return self::PHASE_PREFIX;
+      }
+    }
+
+    return self::PHASE_CONTENT;
+  }
+
+  protected function sliceResults(array $results) {
+    $offset = $this->getOffset();
+    $limit = $this->getLimit();
+
     if ($offset || $limit) {
       if (!$limit) {
         $limit = count($results);
diff --git a/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php b/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
--- a/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
+++ b/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
@@ -13,6 +13,10 @@
   private $parameters = array();
   private $functionStack = array();
   private $isBrowse;
+  private $phase = self::PHASE_CONTENT;
+
+  const PHASE_PREFIX = 'prefix';
+  const PHASE_CONTENT = 'content';
 
   public function setLimit($limit) {
     $this->limit = $limit;
@@ -46,6 +50,10 @@
     return $this;
   }
 
+  public function getPrefixQuery() {
+    return phutil_utf8_strtolower($this->getRawQuery());
+  }
+
   public function getRawQuery() {
     return $this->rawQuery;
   }
@@ -81,6 +89,15 @@
     return $this->isBrowse;
   }
 
+  public function setPhase($phase) {
+    $this->phase = $phase;
+    return $this;
+  }
+
+  public function getPhase() {
+    return $this->phase;
+  }
+
   public function getDatasourceURI() {
     $uri = new PhutilURI('/typeahead/class/'.get_class($this).'/');
     $uri->setQueryParams($this->parameters);
@@ -106,6 +123,13 @@
   abstract public function getDatasourceApplicationClass();
   abstract public function loadResults();
 
+  protected function loadResultsForPhase($phase, $limit) {
+    // By default, sources just load all of their results in every phase and
+    // rely on filtering at a higher level to sequence phases correctly.
+    $this->setLimit($limit);
+    return $this->loadResults();
+  }
+
   protected function didLoadResults(array $results) {
     return $results;
   }
diff --git a/src/applications/typeahead/storage/PhabricatorTypeaheadResult.php b/src/applications/typeahead/storage/PhabricatorTypeaheadResult.php
--- a/src/applications/typeahead/storage/PhabricatorTypeaheadResult.php
+++ b/src/applications/typeahead/storage/PhabricatorTypeaheadResult.php
@@ -18,6 +18,7 @@
   private $unique;
   private $autocomplete;
   private $attributes = array();
+  private $phase;
 
   public function setIcon($icon) {
     $this->icon = $icon;
@@ -154,6 +155,7 @@
       $this->tokenType,
       $this->unique ? 1 : null,
       $this->autocomplete,
+      $this->phase,
     );
     while (end($data) === null) {
       array_pop($data);
@@ -211,4 +213,13 @@
     return $this;
   }
 
+  public function setPhase($phase) {
+    $this->phase = $phase;
+    return $this;
+  }
+
+  public function getPhase() {
+    return $this->phase;
+  }
+
 }