# swiftlang/swift-llbuild

A low-level build system, used by Xcode and the Swift Package Manager

Repository: https://github.com/swiftlang/swift-llbuild
Canonical: https://ross.abutalabs.com/products/swift-llbuild
Language: C++
License: Apache-2.0
License Family: permissive
Topics: build-system, swift, llbuild, llvm, build-tool
Last push: 2026-09-03T00:05:39+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 100, release rhythm 81, longevity 100
- inputs: {"age_days": 3967, "days_push": 0, "days_rel": 131, "gap_med": 0, "n_releases_24m": 12}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1277, forks 236 (observed 2026-09-03T02:15:18.291192+00:00)

## What it is
llbuild is a low-level, library-based build system designed as a reusable and scalable build engine capable of handling dependency graphs with millions of nodes. It powers Swift Package Manager and Xcode and includes a CLI that can build Ninja manifests as a Ninja-compatible replacement.

## Use cases
- build swift packages with a custom build engine
- replace ninja with a compatible build tool
- embed a build engine in a bespoke build system
- build large projects like llvm and clang from ninja manifests
- profile build performance with chromium trace files
- construct a custom build system on a scalable engine

## When to choose
- you need an embeddable, library-based build engine rather than a fixed build file syntax
- you work on Swift tooling or Swift Package Manager internals
- you want a Ninja-compatible builder with build tracing support
- you need to scale builds to very large dependency graphs

## When to avoid
- you just want a simple, conventional build system with a friendly syntax like CMake or Bazel
- you need full Ninja feature compatibility rather than a subset
- you are not building in the Swift/Apple toolchain ecosystem and have no need for a custom engine

## Facets
- artifact type: library
- maturity: active
- function: build-tool, parser, cli, developer-tools
- domain: developer-tools, compilers, programming-languages
- platform: cpp, cross-platform
- tags: build-engine, ninja, swift-package-manager, xcode, dependency-graph, embeddable, command-line, macos, linux, swift

## Member repositories
- swiftlang/swift-llbuild (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-09-03T02:15:18.291192+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T05:02:47.483009+00:00, confidence not recorded.
  - readme: https://github.com/swiftlang/swift-llbuild (fetched 2026-09-03T02:15:18.291192+00:00, sha e2a3b5932750)
- Data as of 2026-08-30T08:39:29.467469+00:00.