diff --git a/resources/sql/patches/20130914.usercustom.sql b/resources/sql/patches/20130914.usercustom.sql
new file mode 100644
index 0000000000..3e7cbb40be
--- /dev/null
+++ b/resources/sql/patches/20130914.usercustom.sql
@@ -0,0 +1,21 @@
+CREATE TABLE {$NAMESPACE}_user.user_customfieldstringindex (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  objectPHID VARCHAR(64) NOT NULL COLLATE utf8_bin,
+  indexKey VARCHAR(12) NOT NULL COLLATE utf8_bin,
+  indexValue LONGTEXT NOT NULL COLLATE utf8_general_ci,
+
+  KEY `key_join` (objectPHID, indexKey, indexValue(64)),
+  KEY `key_find` (indexKey, indexValue(64))
+
+) ENGINE=InnoDB, COLLATE utf8_general_ci;
+
+CREATE TABLE {$NAMESPACE}_user.user_customfieldnumericindex (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  objectPHID VARCHAR(64) NOT NULL COLLATE utf8_bin,
+  indexKey VARCHAR(12) NOT NULL COLLATE utf8_bin,
+  indexValue BIGINT NOT NULL,
+
+  KEY `key_join` (objectPHID, indexKey, indexValue),
+  KEY `key_find` (indexKey, indexValue)
+
+) ENGINE=InnoDB, COLLATE utf8_general_ci;
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 819634dc54..e54a375b71 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -1710,6 +1710,8 @@ phutil_register_library_map(array(
     'PhabricatorUserConfiguredCustomField' => 'applications/people/customfield/PhabricatorUserConfiguredCustomField.php',
     'PhabricatorUserConfiguredCustomFieldStorage' => 'applications/people/storage/PhabricatorUserConfiguredCustomFieldStorage.php',
     'PhabricatorUserCustomField' => 'applications/people/customfield/PhabricatorUserCustomField.php',
+    'PhabricatorUserCustomFieldNumericIndex' => 'applications/people/storage/PhabricatorUserCustomFieldNumericIndex.php',
+    'PhabricatorUserCustomFieldStringIndex' => 'applications/people/storage/PhabricatorUserCustomFieldStringIndex.php',
     'PhabricatorUserDAO' => 'applications/people/storage/PhabricatorUserDAO.php',
     'PhabricatorUserEditor' => 'applications/people/editor/PhabricatorUserEditor.php',
     'PhabricatorUserEmail' => 'applications/people/storage/PhabricatorUserEmail.php',
@@ -3857,6 +3859,8 @@ phutil_register_library_map(array(
     ),
     'PhabricatorUserConfiguredCustomFieldStorage' => 'PhabricatorCustomFieldStorage',
     'PhabricatorUserCustomField' => 'PhabricatorCustomField',
+    'PhabricatorUserCustomFieldNumericIndex' => 'PhabricatorCustomFieldNumericIndexStorage',
+    'PhabricatorUserCustomFieldStringIndex' => 'PhabricatorCustomFieldStringIndexStorage',
     'PhabricatorUserDAO' => 'PhabricatorLiskDAO',
     'PhabricatorUserEditor' => 'PhabricatorEditor',
     'PhabricatorUserEmail' => 'PhabricatorUserDAO',
diff --git a/src/applications/people/customfield/PhabricatorUserConfiguredCustomField.php b/src/applications/people/customfield/PhabricatorUserConfiguredCustomField.php
index 456f76f609..f324ca313a 100644
--- a/src/applications/people/customfield/PhabricatorUserConfiguredCustomField.php
+++ b/src/applications/people/customfield/PhabricatorUserConfiguredCustomField.php
@@ -18,4 +18,12 @@ final class PhabricatorUserConfiguredCustomField
     return new PhabricatorUserConfiguredCustomFieldStorage();
   }
 
+  protected function newStringIndexStorage() {
+    return new PhabricatorUserCustomFieldStringIndex();
+  }
+
+  protected function newNumericIndexStorage() {
+    return new PhabricatorUserCustomFieldNumericIndex();
+  }
+
 }
diff --git a/src/applications/people/query/PhabricatorPeopleQuery.php b/src/applications/people/query/PhabricatorPeopleQuery.php
index afb5a67542..0fafe6c484 100644
--- a/src/applications/people/query/PhabricatorPeopleQuery.php
+++ b/src/applications/people/query/PhabricatorPeopleQuery.php
@@ -101,11 +101,12 @@ final class PhabricatorPeopleQuery
 
     $data = queryfx_all(
       $conn_r,
-      'SELECT * FROM %T user %Q %Q %Q %Q',
+      'SELECT * FROM %T user %Q %Q %Q %Q %Q',
       $table->getTableName(),
       $this->buildJoinsClause($conn_r),
       $this->buildWhereClause($conn_r),
       $this->buildOrderClause($conn_r),
+      $this->buildApplicationSearchGroupClause($conn_r),
       $this->buildLimitClause($conn_r));
 
     if ($this->needPrimaryEmail) {
@@ -181,6 +182,8 @@ final class PhabricatorPeopleQuery
         $email_table->getTableName());
     }
 
+    $joins[] = $this->buildApplicationSearchJoinClause($conn_r);
+
     $joins = implode(' ', $joins);
     return  $joins;
   }
@@ -270,4 +273,8 @@ final class PhabricatorPeopleQuery
     return 'user.id';
   }
 
+  protected function getApplicationSearchObjectPHIDColumn() {
+    return 'user.phid';
+  }
+
 }
diff --git a/src/applications/people/query/PhabricatorPeopleSearchEngine.php b/src/applications/people/query/PhabricatorPeopleSearchEngine.php
index 0a52a437ec..2c9074957a 100644
--- a/src/applications/people/query/PhabricatorPeopleSearchEngine.php
+++ b/src/applications/people/query/PhabricatorPeopleSearchEngine.php
@@ -3,6 +3,10 @@
 final class PhabricatorPeopleSearchEngine
   extends PhabricatorApplicationSearchEngine {
 
+  public function getCustomFieldObject() {
+    return new PhabricatorUser();
+  }
+
   public function buildSavedQueryFromRequest(AphrontRequest $request) {
     $saved = new PhabricatorSavedQuery();
 
@@ -14,6 +18,8 @@ final class PhabricatorPeopleSearchEngine
     $saved->setParameter('createdStart', $request->getStr('createdStart'));
     $saved->setParameter('createdEnd', $request->getStr('createdEnd'));
 
+    $this->readCustomFieldsFromRequest($request, $saved);
+
     return $saved;
   }
 
@@ -57,6 +63,9 @@ final class PhabricatorPeopleSearchEngine
     if ($end) {
       $query->withDateCreatedBefore($end);
     }
+
+    $this->applyCustomFieldsToQuery($query, $saved);
+
     return $query;
   }
 
@@ -101,6 +110,8 @@ final class PhabricatorPeopleSearchEngine
             pht('Show only System Agents.'),
             $is_system_agent));
 
+    $this->appendCustomFieldsToForm($form, $saved);
+
     $this->buildDateRange(
       $form,
       $saved,
diff --git a/src/applications/people/storage/PhabricatorUserCustomFieldNumericIndex.php b/src/applications/people/storage/PhabricatorUserCustomFieldNumericIndex.php
new file mode 100644
index 0000000000..0f36bd8e57
--- /dev/null
+++ b/src/applications/people/storage/PhabricatorUserCustomFieldNumericIndex.php
@@ -0,0 +1,11 @@
+<?php
+
+final class PhabricatorUserCustomFieldNumericIndex
+  extends PhabricatorCustomFieldNumericIndexStorage {
+
+  public function getApplicationName() {
+    return 'user';
+  }
+
+}
+
diff --git a/src/applications/people/storage/PhabricatorUserCustomFieldStringIndex.php b/src/applications/people/storage/PhabricatorUserCustomFieldStringIndex.php
new file mode 100644
index 0000000000..399385c8cc
--- /dev/null
+++ b/src/applications/people/storage/PhabricatorUserCustomFieldStringIndex.php
@@ -0,0 +1,11 @@
+<?php
+
+final class PhabricatorUserCustomFieldStringIndex
+  extends PhabricatorCustomFieldStringIndexStorage {
+
+  public function getApplicationName() {
+    return 'user';
+  }
+
+}
+
diff --git a/src/applications/search/engine/PhabricatorApplicationSearchEngine.php b/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
index 63f297a727..74496d9cf7 100644
--- a/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
+++ b/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
@@ -15,6 +15,7 @@ abstract class PhabricatorApplicationSearchEngine {
 
   private $viewer;
   private $errors = array();
+  private $customFields = false;
 
   public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
@@ -370,4 +371,153 @@ abstract class PhabricatorApplicationSearchEngine {
   }
 
 
+/* -(  Application Search  )------------------------------------------------- */
+
+
+  /**
+   * Retrieve an object to use to define custom fields for this search.
+   *
+   * To integrate with custom fields, subclasses should override this method
+   * and return an instance of the application object which implements
+   * @{interface:PhabricatorCustomFieldInterface}.
+   *
+   * @return PhabricatorCustomFieldInterface|null Object with custom fields.
+   * @task appsearch
+   */
+  public function getCustomFieldObject() {
+    return null;
+  }
+
+
+  /**
+   * Get the custom fields for this search.
+   *
+   * @return PhabricatorCustomFieldList|null Custom fields, if this search
+   *   supports custom fields.
+   * @task appsearch
+   */
+  public function getCustomFieldList() {
+    if ($this->customFields === false) {
+      $object = $this->getCustomFieldObject();
+      if ($object) {
+        $fields = PhabricatorCustomField::getObjectFields(
+          $object,
+          PhabricatorCustomField::ROLE_APPLICATIONSEARCH);
+      } else {
+        $fields = null;
+      }
+      $this->customFields = $fields;
+    }
+    return $this->customFields;
+  }
+
+
+  /**
+   * Moves data from the request into a saved query.
+   *
+   * @param AphrontRequest Request to read.
+   * @param PhabricatorSavedQuery Query to write to.
+   * @return void
+   * @task appsearch
+   */
+  protected function readCustomFieldsFromRequest(
+    AphrontRequest $request,
+    PhabricatorSavedQuery $saved) {
+
+    $list = $this->getCustomFieldList();
+    if (!$list) {
+      return;
+    }
+
+    foreach ($list->getFields() as $field) {
+      $key = $this->getKeyForCustomField($field);
+      $value = $field->readApplicationSearchValueFromRequest(
+        $this,
+        $request);
+      $saved->setParameter($key, $value);
+    }
+  }
+
+
+  /**
+   * Applies data from a saved query to an executable query.
+   *
+   * @param PhabricatorCursorPagedPolicyAwareQuery Query to constrain.
+   * @param PhabricatorSavedQuery Saved query to read.
+   * @return void
+   */
+  protected function applyCustomFieldsToQuery(
+    PhabricatorCursorPagedPolicyAwareQuery $query,
+    PhabricatorSavedQuery $saved) {
+
+    $list = $this->getCustomFieldList();
+    if (!$list) {
+      return;
+    }
+
+    foreach ($list->getFields() as $field) {
+      $key = $this->getKeyForCustomField($field);
+      $value = $field->applyApplicationSearchConstraintToQuery(
+        $this,
+        $query,
+        $saved->getParameter($key));
+    }
+  }
+
+
+  /**
+   * Get a unique key identifying a field.
+   *
+   * @param PhabricatorCustomField Field to identify.
+   * @return string Unique identifier, suitable for use as an input name.
+   */
+  public function getKeyForCustomField(PhabricatorCustomField $field) {
+    return 'custom:'.$field->getFieldIndex();
+  }
+
+
+  /**
+   * Add inputs to an application search form so the user can query on custom
+   * fields.
+   *
+   * @param AphrontFormView Form to update.
+   * @param PhabricatorSavedQuery Values to prefill.
+   * @return void
+   */
+  protected function appendCustomFieldsToForm(
+    AphrontFormView $form,
+    PhabricatorSavedQuery $saved) {
+
+    $list = $this->getCustomFieldList();
+    if (!$list) {
+      return;
+    }
+
+    $phids = array();
+    foreach ($list->getFields() as $field) {
+      $key = $this->getKeyForCustomField($field);
+      $value = $saved->getParameter($key);
+      $phids[$key] = $field->getRequiredHandlePHIDsForApplicationSearch($value);
+    }
+    $all_phids = array_mergev($phids);
+
+    $handles = array();
+    if ($all_phids) {
+      $handles = id(new PhabricatorHandleQuery())
+        ->setViewer($this->getViewer())
+        ->withPHIDs($all_phids)
+        ->execute();
+    }
+
+    foreach ($list->getFields() as $field) {
+      $key = $this->getKeyForCustomField($field);
+      $value = $saved->getParameter($key);
+      $field->appendToApplicationSearchForm(
+        $this,
+        $form,
+        $value,
+        array_select_keys($handles, $phids[$key]));
+    }
+  }
+
 }
diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
index 67cd14eb81..a44ae8e4c7 100644
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -479,6 +479,19 @@ abstract class PhabricatorApplicationTransactionEditor
 
     $this->didApplyTransactions($xactions);
 
+    if ($object instanceof PhabricatorCustomFieldInterface) {
+      // Maybe this makes more sense to move into the search index itself? For
+      // now I'm putting it here since I think we might end up with things that
+      // need it to be up to date once the next page loads, but if we don't go
+      // there we we could move it into search once search moves to the daemons.
+
+      $fields = PhabricatorCustomField::getObjectFields(
+        $object,
+        PhabricatorCustomField::ROLE_APPLICATIONSEARCH);
+      $fields->readFieldsFromStorage($object);
+      $fields->rebuildIndexes($object);
+    }
+
     return $xactions;
   }
 
diff --git a/src/infrastructure/customfield/field/PhabricatorCustomField.php b/src/infrastructure/customfield/field/PhabricatorCustomField.php
index 3538bc7053..5621e24f10 100644
--- a/src/infrastructure/customfield/field/PhabricatorCustomField.php
+++ b/src/infrastructure/customfield/field/PhabricatorCustomField.php
@@ -569,9 +569,7 @@ abstract class PhabricatorCustomField {
    * @task appsearch
    */
   protected function newStringIndexStorage() {
-    if ($this->proxy) {
-      return $this->proxy->newStringIndexStorage();
-    }
+    // NOTE: This intentionally isn't proxied, to avoid call cycles.
     throw new PhabricatorCustomFieldImplementationIncompleteException($this);
   }
 
@@ -585,9 +583,7 @@ abstract class PhabricatorCustomField {
    * @task appsearch
    */
   protected function newNumericIndexStorage() {
-    if ($this->proxy) {
-      return $this->proxy->newStringIndexStorage();
-    }
+    // NOTE: This intentionally isn't proxied, to avoid call cycles.
     throw new PhabricatorCustomFieldImplementationIncompleteException($this);
   }
 
@@ -604,7 +600,7 @@ abstract class PhabricatorCustomField {
       return $this->proxy->newStringIndex();
     }
 
-    $key = $this->getFieldIndexKey();
+    $key = $this->getFieldIndex();
     return $this->newStringIndexStorage()
       ->setIndexKey($key)
       ->setIndexValue($value);
@@ -622,13 +618,103 @@ abstract class PhabricatorCustomField {
     if ($this->proxy) {
       return $this->proxy->newNumericIndex();
     }
-    $key = $this->getFieldIndexKey();
+    $key = $this->getFieldIndex();
     return $this->newNumericIndexStorage()
       ->setIndexKey($key)
       ->setIndexValue($value);
   }
 
 
+  /**
+   * Read a query value from a request, for storage in a saved query. Normally,
+   * this method should, e.g., read a string out of the request.
+   *
+   * @param PhabricatorApplicationSearchEngine Engine building the query.
+   * @param AphrontRequest Request to read from.
+   * @return wild
+   * @task appsearch
+   */
+  public function readApplicationSearchValueFromRequest(
+    PhabricatorApplicationSearchEngine $engine,
+    AphrontRequest $request) {
+    if ($this->proxy) {
+      return $this->proxy->readApplicationSearchValueFromRequest(
+        $engine,
+        $request);
+    }
+    throw new PhabricatorCustomFieldImplementationIncompleteException($this);
+  }
+
+
+  /**
+   * Constrain a query, given a field value. Generally, this method should
+   * use `with...()` methods to apply filters or other constraints to the
+   * query.
+   *
+   * @param PhabricatorApplicationSearchEngine Engine executing the query.
+   * @param PhabricatorCursorPagedPolicyAwareQuery Query to constrain.
+   * @param wild Constraint provided by the user.
+   * @return void
+   * @task appsearch
+   */
+  public function applyApplicationSearchConstraintToQuery(
+    PhabricatorApplicationSearchEngine $engine,
+    PhabricatorCursorPagedPolicyAwareQuery $query,
+    $value) {
+    if ($this->proxy) {
+      return $this->proxy->applyApplicationSearchConstraintToQuery(
+        $engine,
+        $query,
+        $value);
+    }
+    throw new PhabricatorCustomFieldImplementationIncompleteException($this);
+  }
+
+
+  /**
+   * Append search controls to the interface. If you need handles, use
+   * @{method:getRequiredHandlePHIDsForApplicationSearch} to get them.
+   *
+   * @param PhabricatorApplicationSearchEngine Engine constructing the form.
+   * @param AphrontFormView The form to update.
+   * @param wild Value from the saved query.
+   * @param list<PhabricatorObjectHandle> List of handles.
+   * @return void
+   * @task appsearch
+   */
+  public function appendToApplicationSearchForm(
+    PhabricatorApplicationSearchEngine $engine,
+    AphrontFormView $form,
+    $value,
+    array $handles) {
+    if ($this->proxy) {
+      return $this->proxy->appendToApplicationSearchForm(
+        $engine,
+        $form,
+        $value,
+        $handles);
+    }
+    throw new PhabricatorCustomFieldImplementationIncompleteException($this);
+  }
+
+
+  /**
+   * Return a list of PHIDs which @{method:appendToApplicationSearchForm} needs
+   * handles for. This is primarily useful if the field stores PHIDs and you
+   * need to (for example) render a tokenizer control.
+   *
+   * @param wild Value from the saved query.
+   * @return list<phid> List of PHIDs.
+   * @task appsearch
+   */
+  public function getRequiredHandlePHIDsForApplicationSearch($value) {
+    if ($this->proxy) {
+      return $this->proxy->getRequiredHandlePHIDsForApplicationSearch($value);
+    }
+    return array();
+  }
+
+
 /* -(  ApplicationTransactions  )-------------------------------------------- */
 
 
diff --git a/src/infrastructure/customfield/field/PhabricatorCustomFieldList.php b/src/infrastructure/customfield/field/PhabricatorCustomFieldList.php
index e5d17822f8..d4b9f0747e 100644
--- a/src/infrastructure/customfield/field/PhabricatorCustomFieldList.php
+++ b/src/infrastructure/customfield/field/PhabricatorCustomFieldList.php
@@ -151,4 +151,72 @@ final class PhabricatorCustomFieldList extends Phobject {
     return $xactions;
   }
 
+
+  /**
+   * Publish field indexes into index tables, so ApplicationSearch can search
+   * them.
+   *
+   * @return void
+   */
+  public function rebuildIndexes(PhabricatorCustomFieldInterface $object) {
+    $indexes = array();
+    $index_keys = array();
+
+    $phid = $object->getPHID();
+
+    $role = PhabricatorCustomField::ROLE_APPLICATIONSEARCH;
+    foreach ($this->fields as $field) {
+      if (!$field->shouldEnableForRole($role)) {
+        continue;
+      }
+
+      $index_keys[$field->getFieldIndex()] = true;
+
+      foreach ($field->buildFieldIndexes() as $index) {
+        $index->setObjectPHID($phid);
+        $indexes[$index->getTableName()][] = $index;
+      }
+    }
+
+    if (!$indexes) {
+      return;
+    }
+
+    $any_index = head(head($indexes));
+    $conn_w = $any_index->establishConnection('w');
+
+    foreach ($indexes as $table => $index_list) {
+      $sql = array();
+      foreach ($index_list as $index) {
+        $sql[] = $index->formatForInsert($conn_w);
+      }
+      $indexes[$table] = $sql;
+    }
+
+    $any_index->openTransaction();
+
+      foreach ($indexes as $table => $sql_list) {
+        queryfx(
+          $conn_w,
+          'DELETE FROM %T WHERE objectPHID = %s AND indexKey IN (%Ls)',
+          $table,
+          $phid,
+          array_keys($index_keys));
+
+        if (!$sql_list) {
+          continue;
+        }
+
+        foreach (PhabricatorLiskDAO::chunkSQL($sql_list) as $chunk) {
+          queryfx(
+            $conn_w,
+            'INSERT INTO %T (objectPHID, indexKey, indexValue) VALUES %Q',
+            $table,
+            $chunk);
+        }
+      }
+
+    $any_index->saveTransaction();
+  }
+
 }
diff --git a/src/infrastructure/customfield/field/PhabricatorStandardCustomField.php b/src/infrastructure/customfield/field/PhabricatorStandardCustomField.php
index 20c5526895..6fedc13e77 100644
--- a/src/infrastructure/customfield/field/PhabricatorStandardCustomField.php
+++ b/src/infrastructure/customfield/field/PhabricatorStandardCustomField.php
@@ -56,6 +56,10 @@ final class PhabricatorStandardCustomField
     return $this;
   }
 
+  public function getFieldType() {
+    return $this->fieldType;
+  }
+
   public function getFieldValue() {
     return $this->fieldValue;
   }
@@ -71,6 +75,8 @@ final class PhabricatorStandardCustomField
   }
 
   public function setFieldConfig(array $config) {
+    $this->setFieldType('text');
+
     foreach ($config as $key => $value) {
       switch ($key) {
         case 'name':
@@ -79,6 +85,9 @@ final class PhabricatorStandardCustomField
         case 'type':
           $this->setFieldType($value);
           break;
+        case 'description':
+          $this->setFieldDescription($value);
+          break;
       }
     }
     $this->fieldConfig = $config;
@@ -90,6 +99,7 @@ final class PhabricatorStandardCustomField
   }
 
 
+
 /* -(  PhabricatorCustomField  )--------------------------------------------- */
 
 
@@ -130,7 +140,7 @@ final class PhabricatorStandardCustomField
   }
 
   public function renderEditControl() {
-    $type = $this->getFieldConfigValue('type', 'text');
+    $type = $this->getFieldType();
     switch ($type) {
       case 'text':
       default:
@@ -153,5 +163,75 @@ final class PhabricatorStandardCustomField
     return $this->getFieldValue();
   }
 
+  public function shouldAppearInApplicationSearch() {
+    return $this->getFieldConfigValue('search', false);
+  }
+
+  protected function newStringIndexStorage() {
+    return $this->getApplicationField()->newStringIndexStorage();
+  }
+
+  protected function newNumericIndexStorage() {
+    return $this->getApplicationField()->newNumericIndexStorage();
+  }
+
+  public function buildFieldIndexes() {
+    $type = $this->getFieldType();
+    switch ($type) {
+      case 'text':
+      default:
+        return array(
+          $this->newStringIndex($this->getFieldValue()),
+        );
+    }
+  }
+
+  public function readApplicationSearchValueFromRequest(
+    PhabricatorApplicationSearchEngine $engine,
+    AphrontRequest $request) {
+    $type = $this->getFieldType();
+    switch ($type) {
+      case 'text':
+      default:
+        return $request->getStr('std:'.$this->getFieldIndex());
+    }
+  }
+
+  public function applyApplicationSearchConstraintToQuery(
+    PhabricatorApplicationSearchEngine $engine,
+    PhabricatorCursorPagedPolicyAwareQuery $query,
+    $value) {
+    $type = $this->getFieldType();
+    switch ($type) {
+      case 'text':
+      default:
+        if (strlen($value)) {
+          $query->withApplicationSearchContainsConstraint(
+            $this->newStringIndex(null),
+            $value);
+        }
+        break;
+    }
+  }
+
+  public function appendToApplicationSearchForm(
+    PhabricatorApplicationSearchEngine $engine,
+    AphrontFormView $form,
+    $value,
+    array $handles) {
+
+    $type = $this->getFieldType();
+    switch ($type) {
+      case 'text':
+      default:
+        $form->appendChild(
+          id(new AphrontFormTextControl())
+            ->setLabel($this->getFieldName())
+            ->setName('std:'.$this->getFieldIndex())
+            ->setValue($value));
+        break;
+    }
+
+  }
 
 }
diff --git a/src/infrastructure/customfield/storage/PhabricatorCustomFieldIndexStorage.php b/src/infrastructure/customfield/storage/PhabricatorCustomFieldIndexStorage.php
index 7a01fd4df7..b0780bd1c9 100644
--- a/src/infrastructure/customfield/storage/PhabricatorCustomFieldIndexStorage.php
+++ b/src/infrastructure/customfield/storage/PhabricatorCustomFieldIndexStorage.php
@@ -14,5 +14,6 @@ abstract class PhabricatorCustomFieldIndexStorage
   }
 
   abstract public function formatForInsert(AphrontDatabaseConnection $conn);
+  abstract public function getIndexValueType();
 
 }
diff --git a/src/infrastructure/customfield/storage/PhabricatorCustomFieldNumericIndexStorage.php b/src/infrastructure/customfield/storage/PhabricatorCustomFieldNumericIndexStorage.php
index f7d93456f8..0b98bad40a 100644
--- a/src/infrastructure/customfield/storage/PhabricatorCustomFieldNumericIndexStorage.php
+++ b/src/infrastructure/customfield/storage/PhabricatorCustomFieldNumericIndexStorage.php
@@ -12,4 +12,8 @@ abstract class PhabricatorCustomFieldNumericIndexStorage
       $this->getIndexValue());
   }
 
+  public function getIndexValueType() {
+    return 'int';
+  }
+
 }
diff --git a/src/infrastructure/customfield/storage/PhabricatorCustomFieldStringIndexStorage.php b/src/infrastructure/customfield/storage/PhabricatorCustomFieldStringIndexStorage.php
index 73ccc7597a..1cb840a89f 100644
--- a/src/infrastructure/customfield/storage/PhabricatorCustomFieldStringIndexStorage.php
+++ b/src/infrastructure/customfield/storage/PhabricatorCustomFieldStringIndexStorage.php
@@ -12,4 +12,8 @@ abstract class PhabricatorCustomFieldStringIndexStorage
       $this->getIndexValue());
   }
 
+  public function getIndexValueType() {
+    return 'string';
+  }
+
 }
diff --git a/src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php b/src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php
index 93b0d96412..b05ea23d32 100644
--- a/src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php
+++ b/src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php
@@ -3,12 +3,15 @@
 /**
  * A query class which uses cursor-based paging. This paging is much more
  * performant than offset-based paging in the presence of policy filtering.
+ *
+ * @task appsearch Integration with ApplicationSearch
  */
 abstract class PhabricatorCursorPagedPolicyAwareQuery
   extends PhabricatorPolicyAwareQuery {
 
   private $afterID;
   private $beforeID;
+  private $applicationSearchConstraints = array();
 
   protected function getPagingColumn() {
     return 'id';
@@ -228,4 +231,163 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
     return '('.implode(') OR (', $clauses).')';
   }
 
+
+/* -(  Application Search  )------------------------------------------------- */
+
+
+  /**
+   * Constrain the query with an ApplicationSearch index. This adds a constraint
+   * which requires objects to have one or more corresponding rows in the index
+   * with one of the given values. Combined with appropriate indexes, it can
+   * build the most common types of queries, like:
+   *
+   *   - Find users with shirt sizes "X" or "XL".
+   *   - Find shoes with size "13".
+   *
+   * @param PhabricatorCustomFieldIndexStorage Table where the index is stored.
+   * @param string|list<string> One or more values to filter by.
+   * @task appsearch
+   */
+  public function withApplicationSearchContainsConstraint(
+    PhabricatorCustomFieldIndexStorage $index,
+    $value) {
+
+    $this->applicationSearchConstraints[] = array(
+      'type'  => $index->getIndexValueType(),
+      'cond'  => '=',
+      'table' => $index->getTableName(),
+      'index' => $index->getIndexKey(),
+      'value' => $value,
+    );
+
+    return $this;
+  }
+
+
+  /**
+   * Get the name of the query's primary object PHID column, for constructing
+   * JOIN clauses. Normally (and by default) this is just `"phid"`, but if the
+   * query construction requires a table alias it may be something like
+   * `"task.phid"`.
+   *
+   * @return string Column name.
+   * @task appsearch
+   */
+  protected function getApplicationSearchObjectPHIDColumn() {
+    return 'phid';
+  }
+
+
+  /**
+   * Determine if the JOINs built by ApplicationSearch might cause each primary
+   * object to return multiple result rows. Generally, this means the query
+   * needs an extra GROUP BY clause.
+   *
+   * @return bool True if the query may return multiple rows for each object.
+   * @task appsearch
+   */
+  protected function getApplicationSearchMayJoinMultipleRows() {
+    foreach ($this->applicationSearchConstraints as $constraint) {
+      $type = $constraint['type'];
+      $value = $constraint['value'];
+
+      switch ($type) {
+        case 'string':
+        case 'int':
+          if (count((array)$value) > 1) {
+            return true;
+          }
+          break;
+        default:
+          throw new Exception("Unknown constraint type '{$type}!");
+      }
+    }
+
+    return false;
+  }
+
+
+  /**
+   * Construct a GROUP BY clause appropriate for ApplicationSearch constraints.
+   *
+   * @param AphrontDatabaseConnection Connection executing the query.
+   * @return string Group clause.
+   * @task appsearch
+   */
+  protected function buildApplicationSearchGroupClause(
+    AphrontDatabaseConnection $conn_r) {
+
+    if ($this->getApplicationSearchMayJoinMultipleRows()) {
+      return qsprintf(
+        $conn_r,
+        'GROUP BY %Q',
+        $this->getApplicationSearchObjectPHIDColumn());
+    } else {
+      return '';
+    }
+  }
+
+
+  /**
+   * Construct a JOIN clause appropriate for applying ApplicationSearch
+   * constraints.
+   *
+   * @param AphrontDatabaseConnection Connection executing the query.
+   * @return string Join clause.
+   * @task appsearch
+   */
+  protected function buildApplicationSearchJoinClause(
+    AphrontDatabaseConnection $conn_r) {
+
+    $joins = array();
+    foreach ($this->applicationSearchConstraints as $key => $constraint) {
+      $table = $constraint['table'];
+      $alias = 'appsearch_'.$key;
+      $index = $constraint['index'];
+      $cond = $constraint['cond'];
+      $phid_column = $this->getApplicationSearchObjectPHIDColumn();
+      if ($cond !== '=') {
+        throw new Exception("Unknown constraint condition '{$cond}'!");
+      }
+
+      $type = $constraint['type'];
+      switch ($type) {
+        case 'string':
+          $joins[] = qsprintf(
+            $conn_r,
+            'JOIN %T %T ON %T.objectPHID = %Q
+              AND %T.indexKey = %s
+              AND %T.indexValue IN (%Ls)',
+            $table,
+            $alias,
+            $alias,
+            $phid_column,
+            $alias,
+            $index,
+            $alias,
+            (array)$constraint['value']);
+          break;
+        case 'int':
+          $joins[] = qsprintf(
+            $conn_r,
+            'JOIN %T %T ON %T.objectPHID = %Q
+              AND %T.indexKey = %s
+              AND %T.indexValue IN (%Ld)',
+            $table,
+            $alias,
+            $alias,
+            $phid_column,
+            $alias,
+            $index,
+            $alias,
+            (array)$constraint['value']);
+          break;
+        default:
+          throw new Exception("Unknown constraint type '{$type}'!");
+      }
+    }
+
+    return implode(' ', $joins);
+  }
+
 }
diff --git a/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php b/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
index de0b01b8a7..eb5b7cf99b 100644
--- a/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
+++ b/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
@@ -1592,6 +1592,10 @@ final class PhabricatorBuiltinPatchList extends PhabricatorSQLPatchList {
         'type' => 'php',
         'name' => $this->getPatchPath('20130913.maniphest.1.migratesearch.php'),
       ),
+      '20130914.usercustom.sql' => array(
+        'type' => 'sql',
+        'name' => $this->getPatchPath('20130914.usercustom.sql'),
+      ),
     );
   }
 }