CyanogenMod has finally released the CM 13 Nightly based on Android 6.0.1 for OnePlus X; the OS was under testing for quite some time now and today CyanogenMod has finally decided to launch it officially after many users reported that it is stable enough to use it as a daily driver. OnePlus is yet to roll out Oxygen OS 3.0 for OnePlus X and now with CM 13 build users get to experience the Marshmallow sweetness before the traditional OnePlus Rom. Android 6.0.1 brings new app permissions, Doze mode that will kill all the background tasks when the phone is kept idle for some time thus saving some battery. Web Experience, App Links and Power & Charging.
OnePlus has already rolled out the Marshmallow 6.0.1 update for OnePlus Two based on Oxygen 3.0 while the OnePlus has already got the Marshmallow update based on Cyanogen, though it is no clear when OnePlus will roll out the Oxygen OS based Marshmallow update for OnePlus One and X.
To update your OnePlus X with Marshmallow based on Android 6.0.1, head over to CyanogenMod website and download the Zip file and flash it via Recovery. You will have to manually flash the GAPPS separately even after flashing the ROM.