Google has a multi-year plan to migrate the Android Build system to Bazel. This migration is in early stages, but some changes can be made to current build files to start preparing them for Bazel. At the completion of the migration Bazel will replace all existing build systems and build configuration systems in AOSP (Make, Kati, Soong, Make-based product configuration).
Bazel is Google's open source build system. Bazel projects are described using BUILD files, which are read and analyzed by Bazel into a graph of actions to execute (like compiling a .cc file). After analysis is complete, Bazel executes these actions using tools like clang and javac.
Bazel will provide faster, more reliable builds of AOSP. Bazel should also make it easier to build AOSP in custom configurations.
For more information about the Bazel build system, see bazel.build. To watch an overview of migrating AOSP to use Bazel, see Bazel for Android Open Source Platform (AOSP).