Build Systems Engineer (Bazel)

What MatX Is Building

MatX builds custom AI accelerator silicon. The build system is the backbone: it wires together RTL, a stack of commercial EDA tools (simulation, synthesis, place-and-route, lint/CDC), and a Rust/Python software stack into one hermetic, reproducible pipeline. We run on Bazel with bzlmod, RBE, custom rules, and a small but tight set of platform-level abstractions.

You'll join a small group that owns the build graph, the toolchains, the rules that wrap each EDA tool, and the CI infrastructure that keeps thousands of targets green.

What You’ll Do Here

• New EDA tool integrations. Wrap a closed-source tool in a hermetic Bazel rule with proper providers, runfiles, and execution constraints. Add a new front-end stage to an existing toolchain; add a rule for test variants that share configuration; wire a third-party generator into our verilog graph as a first-class dep
• Bazel version migrations. Lead upgrades (8.x → 9.x) and the bzlmod/MODULE.bazel housekeeping that comes with them
• Hermeticity work. Hunt down the implicit assumptions: system Python, system gcc, leaked /usr/bin deps, host-state in tests. Replace them with hermetic toolchains and tracked inputs
• Refactors that delete code. Rewrite a fragmented family of test macros in terms of one shared rule. Remove a homegrown wrapper rule once upstream covers the case. Extract a common aspect helper used by three places that duplicated it. The good PRs net negative
• Build performance. Persistent workers for slow tools, RBE configs, action graph hygiene, cache-key debugging when something silently rebuilds
• CI infrastructure. GitHub Actions self-hosted runners on GCE COS, Buildbarn workers, monitoring, rolling upgrades
• PRs are small and frequent. Median is +50/-30. Big refactors arrive as a series of mechanical commits, each individually reviewable
• Reviews are real. We comment, ask questions, request changes. Reviews are how we share the build system across the team — not rubber-stamping
• Negative diffs are celebrated. "Remove unused X" and "Replace ad-hoc Y with Z" are first-class contributions
• You'll teach the rest of the team Bazel. Half the company writes RTL or Rust, not Starlark. Good rules let them stay in their domain. Good docstrings (and stardoc) keep them self-serve
• You'll work tightly with at least one of us. Most non-trivial changes are pair-designed before code. Fast feedback loops, whiteboard sessions, no async-only collaboration
• Lean on AI, but stay persnickety. We use Claude Code and similar tools heavily — for prototypes, refactors, scripts, even rule scaffolding. We also reject most of what they produce on the first pass. You'll steer the model hard toward your taste, push back on the easy answer, and review every line you commit as if you wrote it. Auto-generated PRs that pass tests but miss the point are not what we want

Who You Are

• Deep build-system fluency. Rules, providers (or equivalent), aspects, toolchains, platforms, configuration/select, transitions, query. You can read a build-system file — .bzl, Buck2 BUCK, Shake Rules.hs, whatever — and predict what its action graph will look like. Bazel-native is a plus; we'll trade six weeks of Starlark ramp for the right taste.
  We hire on build-system fluency, not Bazel-keyword-matching. If you've done equivalent work in Buck2, Shake/Hadrian, Pants, Nix, or a homegrown Blaze-shaped system, read the bullets as concepts — Bazel is what you'll write here, but the principles port. Be honest about ramp on Starlark and bzlmod.
• bzlmod / MODULE.bazel. Module extensions, lockfile management, vendoring third-party deps cleanly
• Remote execution. RBE, Buck2 RE, BuildBuddy, BuildBarn, your own — they all teach the same lessons. Cache-key debugging, Build without the Bytes, diagnosing "works locally, fails remote." If you've owned one end-to-end, the next one is a port
• Comfort in Rust / Python / shell / Starlark. You might read all four in any given week

Bonus Points If You Have

• Build graph is the source of truth. "If two things must stay in sync, make one depend on the other." Allergic to parallel lists in workflow YAML, Python arrays, and .bzl dicts that drift
• Don't parse what you can generate. If a tool has the structured data internally, have it write structured output. Parsing human-readable reports is a temporary bridge, not a design
• Split build from check. A rule that produces artifacts always succeeds; a separate _test target gates on quality. Empty dashboards because the build broke are unacceptable
• Let Bazel parallelize, not the orchestrator. One bazel build --keep_going over N matrix jobs that each warm up Bazel
• Encode execution constraints in the rule, not the invocation. No README accumulating per-tool --strategy=..., --remote_download_outputs=..., --sandbox_debug incantations. execution_requirements belongs on the action
• Compose at the boundary. Dev and prod differ only in where data comes from — share the components, swap the source. No parallel dev-only servers
• Smart targets over comprehensions. A direct rule call per file beats a list-comprehension factory plus three parallel side dicts
• Sort keys for determinism. The bytes of an emitted file are a function of semantic content, not iteration order
• Internal vs external API. Collapsing N files to 1 is a free improvement when you own both ends. It's a breaking change when someone else's scripts source those files by name
• Migrated a non-trivial codebase between major build-system versions or paradigms — WORKSPACE → bzlmod, Buck1 → Buck2, Make → Shake, or similar. Bonus if you led the bzlmod / MODULE.bazel housekeeping
• Written rules that wrap closed-source tools (EDA, ML, codegen) and made them hermetic and remote-executable — in Bazel, Buck2, Shake, or otherwise. The craft is the hermetic wrapper, not the syntax
• Owned a remote-execution deployment end-to-end — Bazel RBE, Buck2 RE, BuildBarn, BuildBuddy, in-house — including diagnosing cache poisoning, toolchain drift, or remote-vs-local divergence

Compensation

The US base salary for this full-time position is determined based on a variety of factors including role, experience, location, job related skills, and relevant education and training. Career length is only a guideline for compensation.

• Early Career - $120,000 - $250,000 + equity
• Mid Career - $175,000 - $362,500 + equity
• Senior Career - $250,000 - $475,000 + equity

What We Offer

• A Stake in our success A cash/equity mix that fits your needs, and option to do early exercise
• Health & Wellness Company subsidized Health, Dental, Vision, and Life insurance; Pre-tax Health Savings Accounts with generous company contribution (even if you don’t)
• Time To Recharge 4 weeks paid time off (accrued), 12 company holidays, and 3 weeks remote/flexible work per year
• Support to Parents Up to 12 weeks of paid parental leave, regardless of your path to parenthood
• Learning & Development $1,500 yearly towards your professional development e.g. conferences, courses, and other learning opportunities
• Team Connection Team Lunches, quarterly off-sites, and regular town halls
• Financial Wellbeing 401K and/or Roth IRA, with 5% company contribution, even if you don’t!
• Flexible Spending Accounts Pre-tax spend accounts for medical, dental/vision, dependent care, parking, and transit expenses
• Commute On Us For those commuting up to 1 hour, put your rideshare cost on our company card and reclaim the drive-time to get work done!
• MatX E[x]tras $50 per month to use on the perks you care about most 
• Remote Perks We work remotely Monday & Friday, supported by home-tech setup, and remote wifi expense reimbursement

As part of our dedication to the diversity of our team and our focus on creating an inviting and inclusive work experience, MatX is committed to a policy of Equal Employment Opportunity and will not discriminate against an applicant or employee on the basis of race, color, religion, creed, national origin or ancestry, sex, gender, gender identity, gender expression, sexual orientation, age, physical or mental disability, medical condition, marital/domestic partner status, military and veteran status, genetic information or any other legally recognized protected basis under federal, state or local laws, regulations or ordinances.

All candidates must be authorized to work in the United States and work from our offices in Mountain View Tuesdays-Thursdays.

This position requires access to information that is subject to U.S. export controls. This offer of employment is contingent upon the applicants capacity to perform job functions in compliance with U.S. export control laws without obtaining a license from U.S. export control authorities.

MatX does not accept unsolicited resumes from individual recruiters or third-party recruiting agencies in response to job postings. No fee will be paid to third parties who submit unsolicited candidates directly to our hiring managers or People team and any resumes submitted are deemed to be the property of MatX.