diff --git a/core/modules/search/lib/Drupal/search/SearchQuery.php b/core/modules/search/lib/Drupal/search/SearchQuery.php
new file mode 100644
index 00000000000..95103a670f0
--- /dev/null
+++ b/core/modules/search/lib/Drupal/search/SearchQuery.php
@@ -0,0 +1,518 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\search\SearchQuery.
+ */
+
+namespace Drupal\search;
+
+use Drupal\Core\Database\Query\SelectExtender;
+use Drupal\Core\Database\StatementEmpty;
+
+/**
+ * @file
+ * Search query extender and helper functions.
+ */
+
+/**
+ * Do a query on the full-text search index for a word or words.
+ *
+ * This function is normally only called by each module that supports the
+ * indexed search (and thus, implements hook_update_index()).
+ *
+ * Results are retrieved in two logical passes. However, the two passes are
+ * joined together into a single query. And in the case of most simple
+ * queries the second pass is not even used.
+ *
+ * The first pass selects a set of all possible matches, which has the benefit
+ * of also providing the exact result set for simple "AND" or "OR" searches.
+ *
+ * The second portion of the query further refines this set by verifying
+ * advanced text conditions (such as negative or phrase matches).
+ *
+ * The used query object has the tag 'search_$module' and can be further
+ * extended with hook_query_alter().
+ */
+class SearchQuery extends SelectExtender {
+  /**
+   * The search query that is used for searching.
+   *
+   * @var string
+   */
+  protected $searchExpression;
+
+  /**
+   * Type of search (search module).
+   *
+   * This maps to the value of the type column in search_index, and is equal
+   * to the machine-readable name of the module that implements
+   * hook_search_info().
+   *
+   * @var string
+   */
+  protected $type;
+
+  /**
+   * Positive and negative search keys.
+   *
+   * @var array
+   */
+  protected $keys = array('positive' => array(), 'negative' => array());
+
+  /**
+   * Indicates whether the first pass query requires complex conditions (LIKE).
+   *
+   * @var boolean.
+   */
+  protected $simple = TRUE;
+
+  /**
+   * Conditions that are used for exact searches.
+   *
+   * This is always used for the second pass query but not for the first pass,
+   * unless $this->simple is FALSE.
+   *
+   * @var DatabaseCondition
+   */
+  protected $conditions;
+
+  /**
+   * Indicates how many matches for a search query are necessary.
+   *
+   * @var int
+   */
+  protected $matches = 0;
+
+  /**
+   * Array of search words.
+   *
+   * These words have to match against {search_index}.word.
+   *
+   * @var array
+   */
+  protected $words = array();
+
+  /**
+   * Multiplier for the normalized search score.
+   *
+   * This value is calculated by the first pass query and multiplied with the
+   * actual score of a specific word to make sure that the resulting calculated
+   * score is between 0 and 1.
+   *
+   * @var float
+   */
+  protected $normalize;
+
+  /**
+   * Indicates whether the first pass query has been executed.
+   *
+   * @var boolean
+   */
+  protected $executedFirstPass = FALSE;
+
+  /**
+   * Stores score expressions.
+   *
+   * @var array
+   */
+  protected $scores = array();
+
+  /**
+   * Stores arguments for score expressions.
+   *
+   * @var array
+   */
+  protected $scoresArguments = array();
+
+  /**
+   * Total value of all the multipliers.
+   *
+   * @var array
+   */
+  protected $multiply = array();
+
+  /**
+   * Whether or not search expressions were ignored.
+   *
+   * The maximum number of AND/OR combinations exceeded can be configured to
+   * avoid Denial-of-Service attacks. Expressions beyond the limit are ignored.
+   *
+   * @var boolean
+   */
+  protected $expressionsIgnored = FALSE;
+
+  /**
+   * Sets up the search query expression.
+   *
+   * @param $query
+   *   A search query string, which can contain options.
+   * @param $module
+   *   The search module. This maps to {search_index}.type in the database.
+   *
+   * @return
+   *   The SearchQuery object.
+   */
+  public function searchExpression($expression, $module) {
+    $this->searchExpression = $expression;
+    $this->type = $module;
+
+    return $this;
+  }
+
+  /**
+   * Applies a search option and removes it from the search query string.
+   *
+   * These options are in the form option:value,value2,value3.
+   *
+   * @param $option
+   *   Name of the option.
+   * @param $column
+   *   Name of the database column to which the value should be applied.
+   *
+   * @return
+   *   TRUE if a value for that option was found, FALSE if not.
+   */
+  public function setOption($option, $column) {
+    if ($values = search_expression_extract($this->searchExpression, $option)) {
+      $or = db_or();
+      foreach (explode(',', $values) as $value) {
+        $or->condition($column, $value);
+      }
+      $this->condition($or);
+      $this->searchExpression = search_expression_insert($this->searchExpression, $option);
+      return TRUE;
+    }
+    return FALSE;
+  }
+
+  /**
+   * Parses the search query into SQL conditions.
+   *
+   * We build two queries that match the dataset bodies.
+   */
+  protected function parseSearchExpression() {
+    // Matchs words optionally prefixed by a dash. A word in this case is
+    // something between two spaces, optionally quoted.
+    preg_match_all('/ (-?)("[^"]+"|[^" ]+)/i', ' ' .  $this->searchExpression , $keywords, PREG_SET_ORDER);
+
+    if (count($keywords) ==  0) {
+      return;
+    }
+
+    // Classify tokens.
+    $or = FALSE;
+    $warning = '';
+    $limit_combinations = variable_get('search_and_or_limit', 7);
+    // The first search expression does not count as AND.
+    $and_count = -1;
+    $or_count = 0;
+    foreach ($keywords as $match) {
+      if ($or_count && $and_count + $or_count >= $limit_combinations) {
+        // Ignore all further search expressions to prevent Denial-of-Service
+        // attacks using a high number of AND/OR combinations.
+        $this->expressionsIgnored = TRUE;
+        break;
+      }
+      $phrase = FALSE;
+      // Strip off phrase quotes.
+      if ($match[2]{0} == '"') {
+        $match[2] = substr($match[2], 1, -1);
+        $phrase = TRUE;
+        $this->simple = FALSE;
+      }
+      // Simplify keyword according to indexing rules and external
+      // preprocessors. Use same process as during search indexing, so it
+      // will match search index.
+      $words = search_simplify($match[2]);
+      // Re-explode in case simplification added more words, except when
+      // matching a phrase.
+      $words = $phrase ? array($words) : preg_split('/ /', $words, -1, PREG_SPLIT_NO_EMPTY);
+      // Negative matches.
+      if ($match[1] == '-') {
+        $this->keys['negative'] = array_merge($this->keys['negative'], $words);
+      }
+      // OR operator: instead of a single keyword, we store an array of all
+      // OR'd keywords.
+      elseif ($match[2] == 'OR' && count($this->keys['positive'])) {
+        $last = array_pop($this->keys['positive']);
+        // Starting a new OR?
+        if (!is_array($last)) {
+          $last = array($last);
+        }
+        $this->keys['positive'][] = $last;
+        $or = TRUE;
+        $or_count++;
+        continue;
+      }
+      // AND operator: implied, so just ignore it.
+      elseif ($match[2] == 'AND' || $match[2] == 'and') {
+        $warning = $match[2];
+        continue;
+      }
+
+      // Plain keyword.
+      else {
+        if ($match[2] == 'or') {
+          $warning = $match[2];
+        }
+        if ($or) {
+          // Add to last element (which is an array).
+          $this->keys['positive'][count($this->keys['positive']) - 1] = array_merge($this->keys['positive'][count($this->keys['positive']) - 1], $words);
+        }
+        else {
+          $this->keys['positive'] = array_merge($this->keys['positive'], $words);
+          $and_count++;
+        }
+      }
+      $or = FALSE;
+    }
+
+    // Convert keywords into SQL statements.
+    $this->conditions = db_and();
+    $simple_and = FALSE;
+    $simple_or = FALSE;
+    // Positive matches.
+    foreach ($this->keys['positive'] as $key) {
+      // Group of ORed terms.
+      if (is_array($key) && count($key)) {
+        $simple_or = TRUE;
+        $any = FALSE;
+        $queryor = db_or();
+        foreach ($key as $or) {
+          list($num_new_scores) = $this->parseWord($or);
+          $any |= $num_new_scores;
+          $queryor->condition('d.data', "% $or %", 'LIKE');
+        }
+        if (count($queryor)) {
+          $this->conditions->condition($queryor);
+          // A group of OR keywords only needs to match once.
+          $this->matches += ($any > 0);
+        }
+      }
+      // Single ANDed term.
+      else {
+        $simple_and = TRUE;
+        list($num_new_scores, $num_valid_words) = $this->parseWord($key);
+        $this->conditions->condition('d.data', "% $key %", 'LIKE');
+        if (!$num_valid_words) {
+          $this->simple = FALSE;
+        }
+        // Each AND keyword needs to match at least once.
+        $this->matches += $num_new_scores;
+      }
+    }
+    if ($simple_and && $simple_or) {
+      $this->simple = FALSE;
+    }
+    // Negative matches.
+    foreach ($this->keys['negative'] as $key) {
+      $this->conditions->condition('d.data', "% $key %", 'NOT LIKE');
+      $this->simple = FALSE;
+    }
+
+    if ($warning == 'or') {
+      drupal_set_message(t('Search for either of the two terms with uppercase <strong>OR</strong>. For example, <strong>cats OR dogs</strong>.'));
+    }
+  }
+
+  /**
+   * Helper function for parseQuery().
+   */
+  protected function parseWord($word) {
+    $num_new_scores = 0;
+    $num_valid_words = 0;
+    // Determine the scorewords of this word/phrase.
+    $split = explode(' ', $word);
+    foreach ($split as $s) {
+      $num = is_numeric($s);
+      if ($num || drupal_strlen($s) >= variable_get('minimum_word_size', 3)) {
+        if (!isset($this->words[$s])) {
+          $this->words[$s] = $s;
+          $num_new_scores++;
+        }
+        $num_valid_words++;
+      }
+    }
+    // Return matching snippet and number of added words.
+    return array($num_new_scores, $num_valid_words);
+  }
+
+  /**
+   * Executes the first pass query.
+   *
+   * This can either be done explicitly, so that additional scores and
+   * conditions can be applied to the second pass query, or implicitly by
+   * addScore() or execute().
+   *
+   * @return
+   *   TRUE if search items exist, FALSE if not.
+   */
+  public function executeFirstPass() {
+    $this->parseSearchExpression();
+
+    if (count($this->words) == 0) {
+      form_set_error('keys', format_plural(variable_get('minimum_word_size', 3), 'You must include at least one positive keyword with 1 character or more.', 'You must include at least one positive keyword with @count characters or more.'));
+      return FALSE;
+    }
+    if ($this->expressionsIgnored) {
+      drupal_set_message(t('Your search used too many AND/OR expressions. Only the first @count terms were included in this search.', array('@count' => variable_get('search_and_or_limit', 7))), 'warning');
+    }
+    $this->executedFirstPass = TRUE;
+
+    if (!empty($this->words)) {
+      $or = db_or();
+      foreach ($this->words as $word) {
+        $or->condition('i.word', $word);
+      }
+      $this->condition($or);
+    }
+    // Build query for keyword normalization.
+    $this->join('search_total', 't', 'i.word = t.word');
+    $this
+      ->condition('i.type', $this->type)
+      ->groupBy('i.type')
+      ->groupBy('i.sid')
+      ->having('COUNT(*) >= :matches', array(':matches' => $this->matches));
+
+    // Clone the query object to do the firstPass query;
+    $first = clone $this->query;
+
+    // For complex search queries, add the LIKE conditions to the first pass query.
+    if (!$this->simple) {
+      $first->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
+      $first->condition($this->conditions);
+    }
+
+    // Calculate maximum keyword relevance, to normalize it.
+    $first->addExpression('SUM(i.score * t.count)', 'calculated_score');
+    $this->normalize = $first
+      ->range(0, 1)
+      ->orderBy('calculated_score', 'DESC')
+      ->execute()
+      ->fetchField();
+
+    if ($this->normalize) {
+      return TRUE;
+    }
+    return FALSE;
+  }
+
+  /**
+   * Adds a custom score expression to the search query.
+   *
+   * Each score expression can optionally use a multiplier, and multiple
+   * expressions are combined.
+   *
+   * @param $score
+   *   The score expression.
+   * @param $arguments
+   *   Custom query arguments for that expression.
+   * @param $multiply
+   *   If set, the score is multiplied with that value. Search query ensures
+   *   that the search scores are still normalized.
+   */
+  public function addScore($score, $arguments = array(), $multiply = FALSE) {
+    if ($multiply) {
+      $i = count($this->multiply);
+      $score = "CAST(:multiply_$i AS DECIMAL) * COALESCE(( " . $score . "), 0) / CAST(:total_$i AS DECIMAL)";
+      $arguments[':multiply_' . $i] = $multiply;
+      $this->multiply[] = $multiply;
+    }
+
+    $this->scores[] = $score;
+    $this->scoresArguments += $arguments;
+
+    return $this;
+  }
+
+  /**
+   * Executes the search.
+   *
+   * If not already done, this executes the first pass query. Then the complex
+   * conditions are applied to the query including score expressions and
+   * ordering.
+   *
+   * @return
+   *   FALSE if the first pass query returned no results, and a database result
+   *   set if there were results.
+   */
+  public function execute()
+  {
+    if (!$this->executedFirstPass) {
+      $this->executeFirstPass();
+    }
+    if (!$this->normalize) {
+      return new StatementEmpty();
+    }
+
+    // Add conditions to query.
+    $this->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
+    $this->condition($this->conditions);
+
+    if (empty($this->scores)) {
+      // Add default score.
+      $this->addScore('i.relevance');
+    }
+
+    if (count($this->multiply)) {
+      // Add the total multiplicator as many times as requested to maintain
+      // normalization as far as possible.
+      $i = 0;
+      $sum = array_sum($this->multiply);
+      foreach ($this->multiply as $total) {
+        $this->scoresArguments[':total_' . $i] = $sum;
+        $i++;
+      }
+    }
+
+    // Replace i.relevance pseudo-field with the actual, normalized value.
+    $this->scores = str_replace('i.relevance', '(' . (1.0 / $this->normalize) . ' * i.score * t.count)', $this->scores);
+    // Convert scores to an expression.
+    $this->addExpression('SUM(' . implode(' + ', $this->scores) . ')', 'calculated_score', $this->scoresArguments);
+
+    if (count($this->getOrderBy()) == 0) {
+      // Add default order after adding the expression.
+      $this->orderBy('calculated_score', 'DESC');
+    }
+
+    // Add tag and useful metadata.
+    $this
+      ->addTag('search_' . $this->type)
+      ->addMetaData('normalize', $this->normalize)
+      ->fields('i', array('type', 'sid'));
+
+    return $this->query->execute();
+  }
+
+  /**
+   * Builds the default count query for SearchQuery.
+   *
+   * Since SearchQuery always uses GROUP BY, we can default to a subquery. We
+   * also add the same conditions as execute() because countQuery() is called
+   * first.
+   */
+  public function countQuery() {
+    // Clone the inner query.
+    $inner = clone $this->query;
+
+    // Add conditions to query.
+    $inner->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
+    $inner->condition($this->conditions);
+
+    // Remove existing fields and expressions, they are not needed for a count
+    // query.
+    $fields =& $inner->getFields();
+    $fields = array();
+    $expressions =& $inner->getExpressions();
+    $expressions = array();
+
+    // Add the sid as the only field and count them as a subquery.
+    $count = db_select($inner->fields('i', array('sid')), NULL, array('target' => 'slave'));
+
+    // Add the COUNT() expression.
+    $count->addExpression('COUNT(*)');
+
+    return $count;
+  }
+}
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 865f17b3b3e..3b1d9cb5f63 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -947,11 +947,14 @@ function user_account_form(&$form, &$form_state) {
     '#weight' => -10,
   );
 
+  // The mail field is NOT required if account originally had no mail set
+  // and the user performing the edit has 'administer users' permission.
+  // This allows users without e-mail address to be edited and deleted.
   $form['account']['mail'] = array(
     '#type' => 'email',
     '#title' => t('E-mail address'),
     '#description' => t('A valid e-mail address. All e-mails from the system will be sent to this address. The e-mail address is not made public and will only be used if you wish to receive a new password or wish to receive certain news or notifications by e-mail.'),
-    '#required' => TRUE,
+    '#required' => !(empty($account->mail) && user_access('administer users')),
     '#default_value' => (!$register ? $account->mail : ''),
   );
 
@@ -1133,7 +1136,7 @@ function user_account_form_validate($form, &$form_state) {
 
   $mail = $form_state['values']['mail'];
 
-  if ((bool) db_select('users')->fields('users', array('uid'))->condition('uid', $account->uid, '<>')->condition('mail', db_like($mail), 'LIKE')->range(0, 1)->execute()->fetchField()) {
+  if (!empty($mail) && (bool) db_select('users')->fields('users', array('uid'))->condition('uid', $account->uid, '<>')->condition('mail', db_like($mail), 'LIKE')->range(0, 1)->execute()->fetchField()) {
     // Format error message dependent on whether the user is logged in or not.
     if ($GLOBALS['user']->uid) {
       form_set_error('mail', t('The e-mail address %email is already taken.', array('%email' => $mail)));
@@ -3794,14 +3797,19 @@ function user_register_submit($form, &$form_state) {
   }
   // No administrator approval required.
   elseif ($account->status || $notify) {
-    $op = $notify ? 'register_admin_created' : 'register_no_approval_required';
-    _user_mail_notify($op, $account);
-    if ($notify) {
-      drupal_set_message(t('A welcome message with further instructions has been e-mailed to the new user <a href="@url">%name</a>.', array('@url' => url($uri['path'], $uri['options']), '%name' => $account->name)));
+    if (empty($account->mail) && $notify) {
+      drupal_set_message(t('The new user <a href="@url">%name</a> was created without an email address, so no welcome message was sent.', array('@url' => url($uri['path'], $uri['options']), '%name' => $account->name)));
     }
     else {
-      drupal_set_message(t('A welcome message with further instructions has been sent to your e-mail address.'));
-      $form_state['redirect'] = '';
+      $op = $notify ? 'register_admin_created' : 'register_no_approval_required';
+      _user_mail_notify($op, $account);
+      if ($notify) {
+        drupal_set_message(t('A welcome message with further instructions has been e-mailed to the new user <a href="@url">%name</a>.', array('@url' => url($uri['path'], $uri['options']), '%name' => $account->name)));
+      }
+      else {
+        drupal_set_message(t('A welcome message with further instructions has been sent to your e-mail address.'));
+        $form_state['redirect'] = '';
+      }
     }
   }
   // Administrator approval required.
diff --git a/core/modules/user/user.test b/core/modules/user/user.test
index 06fbc954fbd..3a3a71300f3 100644
--- a/core/modules/user/user.test
+++ b/core/modules/user/user.test
@@ -836,6 +836,34 @@ class UserCancelTestCase extends DrupalWebTestCase {
     $this->assertFalse(user_load($account->uid), t('User is not found in the database.'));
   }
 
+  /**
+   * Tests deletion of a user account without an e-mail address.
+   */
+  function testUserWithoutEmailCancelByAdmin() {
+    variable_set('user_cancel_method', 'user_cancel_reassign');
+
+    // Create a regular user.
+    $account = $this->drupalCreateUser(array());
+    // This user has no e-mail address.
+    $edit = array('mail' => '');
+    $account = user_save($account, $edit);
+
+    // Create administrative user.
+    $admin_user = $this->drupalCreateUser(array('administer users'));
+    $this->drupalLogin($admin_user);
+
+    // Delete regular user without e-mail address.
+    $this->drupalGet('user/' . $account->uid . '/edit');
+    $this->drupalPost(NULL, NULL, t('Cancel account'));
+    $this->assertRaw(t('Are you sure you want to cancel the account %name?', array('%name' => $account->name)), t('Confirmation form to cancel account displayed.'));
+    $this->assertText(t('Select the method to cancel the account above.'), t('Allows to select account cancellation method.'));
+
+    // Confirm deletion.
+    $this->drupalPost(NULL, NULL, t('Cancel account'));
+    $this->assertRaw(t('%name has been deleted.', array('%name' => $account->name)), t('User deleted.'));
+    $this->assertFalse(user_load($account->uid), t('User is not found in the database.'));
+  }
+
   /**
    * Create an administrative user and mass-delete other users.
    */
@@ -1786,6 +1814,22 @@ class UserEditTestCase extends DrupalWebTestCase {
     $this->drupalLogin($user1);
     $this->drupalLogout();
   }
+
+  /**
+   * Tests editing of a user account without an e-mail address.
+   */
+  function testUserWithoutEmailEdit() {
+    // Test that an admin can edit users without an e-mail address.
+    $admin = $this->drupalCreateUser(array('administer users'));
+    $this->drupalLogin($admin);
+    // Create a regular user.
+    $user1 = $this->drupalCreateUser(array());
+    // This user has no e-mail address.
+    $edit = array('mail' => '');
+    $user1 = user_save($user1, $edit);
+    $this->drupalPost("user/$user1->uid/edit", $edit, t('Save'));
+    $this->assertRaw(t("The changes have been saved."));
+  }
 }
 
 /**