iOS 9.0.1 (build 13A404) is an official Apple over-the-air update for the iPhone 4s, released on 2015-09-23T17:55:21Z. The update package is 895.6 MB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 2c763fe24d4d2ad59f2501d5156ecd32db434f44.zip.