iOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2015-06-30T15:51:22Z. The update package is 488.46 MB. This is a delta (partial) update that requires 8.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 39dd7a7bc8bc0640b76bac9e76c53faaec1027ad.zip.