The TaiG team has released TaiG 2.2.0 to jailbreak iOS 8.4. TaiG 2.2.0 is untethered jailbreak and currently available only for Windows users
The TaiG iOS 8.4 jailbreak tool compatible devices
iPhone 6, iPhone 6 Plus, iPhone 5s, iPhone 5c, iPhone 5 and iPhone 4s
iPad Air 2, iPad mini 3, iPad Air, iPad 4, iPad 3 and iPad 2
iPad mini 1 (1st generation iPad mini), iPad mini 2 (Retina iPad mini), iPad mini 3
iPod touch 5th generation
How To Jailbreak iOS 8.4 with TaiG 2.2.0
1. Download TaiG untethered jailbreak tool latest version on your PC from here.
2. Connect your device to the PC via USB cable
3. Head over to Settings>> Passcode>> enter your Passcode>> Turn Passcode off>> enter Passcode
4. Turn off Find My iPhone from Settings>> iCloud>> Find My iPhone
5. Launch TaiG 2.2.0 tool as an Administrator on your PC.
6. TaiG will detect your device soon, wait for some time. Once it shows that your device has the correct firmware version, uncheck 3K Assistant, which is just below Cydia 1.1.16.
7. Start the jailbreak process now and wait till the process is completed.
8. Your device will reboot automatically now.