Separate php.ini file for each Apache virtual host?

Is it possible to have a separate php.ini file that overrides the default php.ini file for each virtual host? I'm running Apache/2.2.14, PHP 5.3.2-1.

For example, I have several vhosts pointing to domains in my /var/www/ directory:

/var/www/website1.com  
/var/www/website2.com

What I'd like is to be able to place a custom php.ini file in each directory that would override the default values only for that vhost, but keep the original defaults if the value isn't specified:

/var/www/website1.com/htdocs/
/var/www/website1.com/php.ini

Edit
For those interested, I found more info on the topic at How do I set up per-site php.ini files on a LAMP server using NameVirtualHosts?.

If you're using mod_php, you can override the values you wish in httpd.conf. There are these module directives:

php_value - PHP Value Modifier
php_flag - PHP Flag Modifier
php_admin_value - PHP Value Modifier (Admin)
php_admin_flag - PHP Flag Modifier (Admin)

If not, your best shot is PHP FPM (google it).

If you're using cgi (or fastcgi, or fpm, which is fastcgi too), you can use the .user.ini files.

Simply place a .user.ini file in your webroot directory with your php options, as follows:

memory_limit=256M
upload_max_filesize=200M
post_max_size=200M

And php will extend the main php.ini file with that options.