phpize 无法在 Mac OS X Lion 上运行

我尝试安装xdebug，但我收到有关“phpize”的以下错误消息。我该如何解决这个问题？

leny:~ nick$ sudo pecl install xdebug
Password:
downloading xdebug-2.1.2.tgz ...
Starting to download xdebug-2.1.2.tgz (304,229 bytes)
............done: 304,229 bytes
66 source files, building
running: phpize
Configuring for:
PHP Api Version:         20090626
Zend Module Api No:      20090626
Zend Extension Api No:   220090626
Cannot find autoconf. Please check your autoconf installation and the
$PHP_AUTOCONF environment variable. Then, rerun this script.

ERROR: `phpize' failed