Michelangelo van Dam has a post to his site, now that PHP 7 is released, showing you how to get it installed on OSX (Yosemite) for your local development.

Yesterday was the release of PHP7.0.0 and I wanted to have it on my mac as fast as possible. Since I'm still using Mac OS X Yosemite I will post here the steps to upgrade my platform, it might be useful for you too.

He starts with the requirements needed for the installation including XCode to be able to compile the PHP from scratch and the latest download of PHP 7 from php.net. He then talks about the benefits of compiling your own installation and shares a script that he uses to compile the PHP version he wants (based on a command line option). Once this is run the typical make and make install are executed and, if all goes well, your output for a /opt/php7/bin/php -v will look the same as his.