Automated Linux From Scratch or ALFS, is a project that aims to create a generic framework of an extendable system builder and package installer using XML to describe the process.
Its goal is to automate the process of creating an LFS system. It seeks to make the process of building LFS easier and more efficient while still providing flexibility, granting the user total control and insight into the compilation and management of his LFS build.
The LFS and BLFS projects have selected the nALFS implementation as the "official" ALFS implementation. See below for more info.
It's been in production use for over a year now and is under active development. Take a look at the news page for status of the current stable version.
The LFS and BLFS projects official implementation is Neven Has's nALFS. Mark Ellis also has a perl implementation. Next to the official ALFS implementation, there are a number of more or less tested automated LFS build systems available in the section menu.