The official builds will be released very soon but not yet available for most of the devices.
But xda recognized developer contributor dhiru1602 has ported the NameLess ROM based on CyanogenMod 12 Android Lollipop for Samsung Galaxy S3.
WARNING:
Installing custom ROM requires a custom recovery to be installed on your device, which may VOID your warranty and may delete all your data.
Before proceeding further you may consider backup your all data.
Please visit the Disclaimer page below to agree with the risks involved and proceed before flashing this ROM to your phone:
ROM Disclaimer link
KNOWN ISSUES
GPS LOCK
Home button wake does not work
Stock Camera doesn't work. Use Google camera from play store.
Installing custom ROM requires a custom recovery to be installed on your device, which may VOID your warranty and may delete all your data.
Before proceeding further you may consider backup your all data.
Please visit the Disclaimer page below to agree with the risks involved and proceed before flashing this ROM to your phone:
ROM Disclaimer link
KNOWN ISSUES
GPS LOCK
Home button wake does not work
Stock Camera doesn't work. Use Google camera from play store.
- CM 12 Android Lollipop 5.0 for Samsung Galaxy S3
- If you want ROOT then the SuperSU package
This ROM does not contain Google applications like Gmail, drive, maps etc. so download the below GApps zip package.
Google Apps recovery flashable zip download link
Installing Android Lollipop on Samsung Galaxy S3:
COMING FROM OTHER ROM:
STEP 1:
Copy the ROM, GApps and SuperuserSU package to your phone.
STEP 2:
Reboot into recovery and do a Factory Reset/Wipe Data
Format System
Format Dalvik Cache
STEP 3:
Install the ROM, Gapps and superuser zip.
STEP 4:
Reboot your phone to enjoy the ROOTed Android Lollipop on your Samsung Galaxy S3.
UPGRADE NameLess ROM to a NEW RELEASE:
STEP 1:
Just download the ROM zip package and flash it.
No need to wipe or format anything.
SOURCE: xda-developers
Stay tuned to get more such updates