Bazel pre-merge checks

If you don’t care about building LLVM with Bazel, you can stop reading now.

We have set up pre-merge checks for the Bazel build of LLVM (see the README at if you weren’t following past updates). These will trigger on changes to the utils/bazel directory. Additionally, you can join the bazel build phab project to have it trigger on all of your patches.

The builds run on a separate pool of agents, so they don’t interfere with the main pre-merge builds. Results should generally be reported back in about 5 minutes and the build is the same one being run on every commit to the main branch, so is usually green at HEAD. They are also set with -Werror -Wall (plus or minus) and so can give fast feedback on diagnostics.

In the future, we are likely to use the Bazel project to send emails on post-merge failures to commit authors, filtered to those who are opted in.

If you find this useful, feel free to contribute to maintaining the Bazel build by monitoring the status (e.g. you can star the main branch and get emails from Buildkite when it goes red).