OnePlus X was launched back in November 2015 with OxygenOS 2.2.1 based on Android 5.1.1 Lollipop Out Of The Box.
Well Here a Good news for OnePlus X users, OxygenOS 3.1.0 based on Android 6.0.1 Marshmallow is now Finally available for OnePlus X. Though This Firmware is a Community Build and Might Contain few bugs.
Here are some features of This Firmware-
- Android 6.0.1 Marshmallow
- Launcher upgrades
- New icon packs
- Google search bar UI customization
- New wallpaper picker
- Shelf UX improvements
- Long press boards to rearrange or remove
- General system performance improvement
- Settings changes
- New (native Android) app permissions
- New Alert Slider settings with more customization options
- New apps
- OnePlus Music Player
- OnePlus Gallery
- August 1 security patches for Android
You can Download The Firmware from This Download Link, Make sure to keep a backup before flashing this firmware.
Source- OnePlus Forum