Head to System Preferences > Spotlight > Search Results and uncheck those two boxes.

Disable Safari’s Spotlight Suggestions.

Head to Safari > Preferences > Search and uncheck Spotlight Suggestions.

For now, disabling Spotlight seems to cover the biggest suspected privacy intrusion.

Check out logs on GitHub and the threads on Hacker News for more info.

In Yosemite, all Safari Web Searches…| GitHub viaHacker NewsE.T.

Phone Home| GitHub viaHacker News