A quick search found this: Redirecting to Google Groups
It seems Massimo is keen to get a new compiler in, also the conversation is about 4.8.1.
I'm going to check out this, might have a compiled version.
https://groups.google.com/a/arduino.cc/d/msg/developers/21G5w2HbUOg/bJtG94vEEhkJ
Code to build the toolchain on linux32, linux64, mac32 and windows is
available on the atmel-3.4.3 branch at
GitHub - arduino/toolchain-avr: The AVR toolchain used by the Arduino IDE