iOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPhone 4s, released on 2015-06-30T15:51:18Z. The update package is 153.44 MB. This is a delta (partial) update that requires 8.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c627c92ff90b3cc332a5b5882cc62b8effe2038d.zip.