During the Librarization project we picked xhprof as the choice for non-invasive profiling. However xhprof doesn't support PHP 7, and there really hasn't been much movement on it upstream (c.f. https://secure.phabricator.com/T9805).
Apparently https://github.com/tideways/php-profiler-extension#usage-without-tidewaysio-ui is a possible alternative for PHP 7 users who want/need to enable profiling.
Noticed due to https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=846138 (removal of xhprof from debian unstable)