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 213.2 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: a54b8d4f94a82d1adefda7cc540b0ac7ebb2e4f4.zip.