Problem installing on OS X 10.8.4

I have been following the install instructions for Mac here:

I get an error when running buildconf:

20:05:35 $ ./buildconf --with-phpize=/usr/bin/phpize
Configuring for:
PHP Api Version:         20090626
Zend Module Api No:      20090626
Zend Extension Api No:   220090626
rebuilding aclocal.m4
rebuilding configure
make[1]: autoconf: No such file or directory
make[1]: *** [configure] Error 1
make: *** [all] Error 2

Is autoconf created during buildconf or am I missing something? How do I fix this?