diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -252,7 +252,6 @@
     'AphrontMultipartParser' => 'aphront/multipartparser/AphrontMultipartParser.php',
     'AphrontMultipartParserTestCase' => 'aphront/multipartparser/__tests__/AphrontMultipartParserTestCase.php',
     'AphrontMultipartPart' => 'aphront/multipartparser/AphrontMultipartPart.php',
-    'AphrontMySQLDatabaseConnection' => 'infrastructure/storage/connection/mysql/AphrontMySQLDatabaseConnection.php',
     'AphrontMySQLDatabaseConnectionTestCase' => 'infrastructure/storage/__tests__/AphrontMySQLDatabaseConnectionTestCase.php',
     'AphrontMySQLiDatabaseConnection' => 'infrastructure/storage/connection/mysql/AphrontMySQLiDatabaseConnection.php',
     'AphrontNotSupportedQueryException' => 'infrastructure/storage/exception/AphrontNotSupportedQueryException.php',
@@ -6263,7 +6262,6 @@
     'AphrontMultipartParser' => 'Phobject',
     'AphrontMultipartParserTestCase' => 'PhutilTestCase',
     'AphrontMultipartPart' => 'Phobject',
-    'AphrontMySQLDatabaseConnection' => 'AphrontBaseMySQLDatabaseConnection',
     'AphrontMySQLDatabaseConnectionTestCase' => 'PhabricatorTestCase',
     'AphrontMySQLiDatabaseConnection' => 'AphrontBaseMySQLDatabaseConnection',
     'AphrontNotSupportedQueryException' => 'AphrontQueryException',
diff --git a/src/applications/config/check/PhabricatorExtensionsSetupCheck.php b/src/applications/config/check/PhabricatorExtensionsSetupCheck.php
--- a/src/applications/config/check/PhabricatorExtensionsSetupCheck.php
+++ b/src/applications/config/check/PhabricatorExtensionsSetupCheck.php
@@ -19,6 +19,7 @@
       'openssl',
       'mbstring',
       'ctype',
+      'mysqli',
 
       // There is a tiny chance we might not need this, but a significant
       // number of applications require it and it's widely available.
@@ -32,10 +33,6 @@
       }
     }
 
-    if (!extension_loaded('mysqli') && !extension_loaded('mysql')) {
-      $need[] = 'mysqli or mysql';
-    }
-
     if (!$need) {
       return;
     }
diff --git a/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php b/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php
--- a/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php
+++ b/src/applications/config/check/PhabricatorPHPConfigSetupCheck.php
@@ -67,29 +67,7 @@
         ->addPHPConfig('always_populate_raw_post_data');
     }
 
-    if (!extension_loaded('mysqli')) {
-      $summary = pht(
-        'Install the MySQLi extension to improve database behavior.');
-
-      $message = pht(
-        'PHP is currently using the very old "mysql" extension to interact '.
-        'with the database. You should install the newer "mysqli" extension '.
-        'to improve behaviors (like error handling and query timeouts).'.
-        "\n\n".
-        'This software will work with the older extension, but upgrading to '.
-        'the newer extension is recommended.'.
-        "\n\n".
-        'You may be able to install the extension with a command like: %s',
-
-        // NOTE: We're intentionally telling you to install "mysqlnd" here; on
-        // Ubuntu, there's no separate "mysqli" package.
-        phutil_tag('tt', array(), 'sudo apt-get install php-mysqlnd'));
-
-      $this->newIssue('php.mysqli')
-        ->setName(pht('MySQLi Extension Not Available'))
-        ->setSummary($summary)
-        ->setMessage($message);
-    } else if (!defined('MYSQLI_ASYNC')) {
+    if (!defined('MYSQLI_ASYNC')) {
       $summary = pht(
         'Configure the MySQL Native Driver to improve database behavior.');
 
@@ -112,17 +90,10 @@
         ->setMessage($message);
     }
 
-
-    if (extension_loaded('mysqli')) {
-      $infile_key = 'mysqli.allow_local_infile';
-    } else {
-      $infile_key = 'mysql.allow_local_infile';
-    }
-
-    if (ini_get($infile_key)) {
+    if (ini_get('mysqli.allow_local_infile')) {
       $summary = pht(
         'Disable unsafe option "%s" in PHP configuration.',
-        $infile_key);
+        'mysqli.allow_local_infile');
 
       $message = pht(
         'PHP is currently configured to honor requests from any MySQL server '.
@@ -139,13 +110,16 @@
         'dangerous.'.
         "\n\n".
         'To disable this option, set: %s',
-        phutil_tag('tt', array(), pht('%s = 0', $infile_key)));
+        phutil_tag(
+          'tt',
+          array(),
+          pht('%s = 0', 'mysqli.allow_local_infile')));
 
-      $this->newIssue('php.'.$infile_key)
+      $this->newIssue('php.mysqli.allow_local_infile')
         ->setName(pht('Unsafe PHP "Local Infile" Configuration'))
         ->setSummary($summary)
         ->setMessage($message)
-        ->addPHPConfig($infile_key);
+        ->addPHPConfig('mysqli.allow_local_infile');
     }
 
   }
diff --git a/src/docs/user/installation_guide.diviner b/src/docs/user/installation_guide.diviner
--- a/src/docs/user/installation_guide.diviner
+++ b/src/docs/user/installation_guide.diviner
@@ -120,7 +120,7 @@
   - Apache (usually "httpd" or "apache2") (or nginx)
   - MySQL Server (usually "mysqld" or "mysql-server" or "mariadb-server")
   - PHP (usually "php")
-  - Required PHP extensions: mbstring, iconv, mysql (or mysqli), curl, pcntl
+  - Required PHP extensions: mbstring, iconv, mysqli, curl, pcntl
     (these might be something like "php-mysql" or "php-mysqlnd")
   - Optional PHP extensions: gd, zip
 
diff --git a/src/infrastructure/cluster/PhabricatorDatabaseRef.php b/src/infrastructure/cluster/PhabricatorDatabaseRef.php
--- a/src/infrastructure/cluster/PhabricatorDatabaseRef.php
+++ b/src/infrastructure/cluster/PhabricatorDatabaseRef.php
@@ -738,11 +738,7 @@
   }
 
   public static function newRawConnection(array $options) {
-    if (extension_loaded('mysqli')) {
-      return new AphrontMySQLiDatabaseConnection($options);
-    } else {
-      return new AphrontMySQLDatabaseConnection($options);
-    }
+    return new AphrontMySQLiDatabaseConnection($options);
   }
 
 }
diff --git a/src/infrastructure/storage/connection/mysql/AphrontMySQLDatabaseConnection.php b/src/infrastructure/storage/connection/mysql/AphrontMySQLDatabaseConnection.php
deleted file mode 100644
--- a/src/infrastructure/storage/connection/mysql/AphrontMySQLDatabaseConnection.php
+++ /dev/null
@@ -1,160 +0,0 @@
-<?php
-
-final class AphrontMySQLDatabaseConnection
-  extends AphrontBaseMySQLDatabaseConnection {
-
-  public function escapeUTF8String($string) {
-    $this->validateUTF8String($string);
-    return $this->escapeBinaryString($string);
-  }
-
-  public function escapeBinaryString($string) {
-    return mysql_real_escape_string($string, $this->requireConnection());
-  }
-
-  public function getInsertID() {
-    return mysql_insert_id($this->requireConnection());
-  }
-
-  public function getAffectedRows() {
-    return mysql_affected_rows($this->requireConnection());
-  }
-
-  protected function closeConnection() {
-    mysql_close($this->requireConnection());
-  }
-
-  protected function connect() {
-    if (!function_exists('mysql_connect')) {
-      // We have to '@' the actual call since it can spew all sorts of silly
-      // noise, but it will also silence fatals caused by not having MySQL
-      // installed, which has bitten me on three separate occasions. Make sure
-      // such failures are explicit and loud.
-      throw new Exception(
-        pht(
-          'About to call %s, but the PHP MySQL extension is not available!',
-          'mysql_connect()'));
-    }
-
-    $user = $this->getConfiguration('user');
-    $host = $this->getConfiguration('host');
-    $port = $this->getConfiguration('port');
-
-    if ($port) {
-      $host .= ':'.$port;
-    }
-
-    $database = $this->getConfiguration('database');
-
-    $pass = $this->getConfiguration('pass');
-    if ($pass instanceof PhutilOpaqueEnvelope) {
-      $pass = $pass->openEnvelope();
-    }
-
-    $timeout = $this->getConfiguration('timeout');
-    $timeout_ini = 'mysql.connect_timeout';
-    if ($timeout) {
-      $old_timeout = ini_get($timeout_ini);
-      ini_set($timeout_ini, $timeout);
-    }
-
-    try {
-      $conn = @mysql_connect(
-        $host,
-        $user,
-        $pass,
-        $new_link = true,
-        $flags = 0);
-    } catch (Exception $ex) {
-      if ($timeout) {
-        ini_set($timeout_ini, $old_timeout);
-      }
-      throw $ex;
-    }
-
-    if ($timeout) {
-      ini_set($timeout_ini, $old_timeout);
-    }
-
-    if (!$conn) {
-      $errno = mysql_errno();
-      $error = mysql_error();
-      $this->throwConnectionException($errno, $error, $user, $host);
-    }
-
-    if ($database !== null) {
-      $ret = @mysql_select_db($database, $conn);
-      if (!$ret) {
-        $this->throwQueryException($conn);
-      }
-    }
-
-    $ok = @mysql_set_charset('utf8mb4', $conn);
-    if (!$ok) {
-      mysql_set_charset('binary', $conn);
-    }
-
-    return $conn;
-  }
-
-  protected function rawQuery($raw_query) {
-    return @mysql_query($raw_query, $this->requireConnection());
-  }
-
-  /**
-   * @phutil-external-symbol function mysql_multi_query
-   * @phutil-external-symbol function mysql_fetch_result
-   * @phutil-external-symbol function mysql_more_results
-   * @phutil-external-symbol function mysql_next_result
-   */
-  protected function rawQueries(array $raw_queries) {
-    $conn = $this->requireConnection();
-    $results = array();
-
-    if (!function_exists('mysql_multi_query')) {
-      foreach ($raw_queries as $key => $raw_query) {
-        $results[$key] = $this->processResult($this->rawQuery($raw_query));
-      }
-      return $results;
-    }
-
-    if (!mysql_multi_query(implode("\n;\n\n", $raw_queries), $conn)) {
-      $ex = $this->processResult(false);
-      return array_fill_keys(array_keys($raw_queries), $ex);
-    }
-
-    $processed_all = false;
-    foreach ($raw_queries as $key => $raw_query) {
-      $results[$key] = $this->processResult(@mysql_fetch_result($conn));
-      if (!mysql_more_results($conn)) {
-        $processed_all = true;
-        break;
-      }
-      mysql_next_result($conn);
-    }
-
-    if (!$processed_all) {
-      throw new Exception(
-        pht('There are some results left in the result set.'));
-    }
-
-    return $results;
-  }
-
-  protected function freeResult($result) {
-    mysql_free_result($result);
-  }
-
-  protected function fetchAssoc($result) {
-    return mysql_fetch_assoc($result);
-  }
-
-  protected function getErrorCode($connection) {
-    return mysql_errno($connection);
-  }
-
-  protected function getErrorDescription($connection) {
-    return mysql_error($connection);
-  }
-
-}