Feature request from clockworkgeek, posted on GitHub Oct 25, 2014
On a couple of Magento1 sites I've had to configure nginx and have found .user.ini files to be most reliable.  It is significantly easier than editing the system php.ini then restarting PHP-FPM and worrying about automatic updates over writing your work.  Although the exact filename can be changed with user_ini.filename setting I have yet to see any server change this.
For Magento 2 I suggest two files, /.user.ini and /pub/.user.ini, to allow for situations where Magento files are not stored in the web root and are linked to instead.  Their content is derived from the .htaccess.
memory_limit=768M
max_execution_time=18000
session.auto_start=off