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mold

A faster drop-in replacement for Unix linkers, written in Rust, to shorten build times.

GitHub Download v3.0.0
Stars
17.7k
Forks
585
Licence
MIT
Language
Rust
Last update
15 days ago
Type
Dev tool

What it is

mold is a linker, the final build step that combines compiled object files into one executable or shared library. It is a drop-in replacement for existing Unix linkers, so it can be used without changing your source code. Its stated goal is to make the linking step, which can take a long time on large programs, much faster.

  • Speed up incremental debug builds of a large C++ or Rust project by switching the linker
  • Link programs for other CPU architectures such as ARM64 or RISC-V using the supported targets
  • Compare link times against lld or wild using the benchmark suite the author published

Great for

  • Developers working on large C, C++, or Rust programs with slow link times
  • Teams doing frequent debug-edit-rebuild cycles
  • Linux users on the supported architectures who want to try a faster linker
  • Projects whose build system already lets them pass a compiler flag like -fuse-ld=mold

Not ideal for

  • Developers on macOS or Windows, since the README only describes Unix-style linking and lists Windows only as a release zip without detail (reason: unclear platform support from the README)
  • Small projects where link time is already negligible (reason: the benefit only matters when linking is a bottleneck)
  • People who need a linker feature set the README does not describe (reason: the README does not document full compatibility details)
Step-by-step guide: how to use moldInstall, first run, examples, tips and FAQs

How to get it

  1. 1

    Clone and build from source

    You'll need: Rust 1.95 or later (or install via rustup) · Git · A C compiler such as GCC or Clang

    Clone the repository

    git clone https://github.com/rui314/mold.git

    Build the release binary

    cd mold && cargo build --release

    Install under /usr/local

    sudo ./install-mold.sh
  2. 2

    Run it

    • Build mold with cargo build --release, or install it with the script.
    • Find the binary at target/release/mold, or use the installed copy.
    • Add -fuse-ld=mold to your Clang or GCC 12.1.0+ linker flags.
    • Rebuild your project and compare the link time.
  3. 3

    Get the most out of it

    • Use the -B option with /usr/local/libexec/mold if you have an older GCC that does not accept -fuse-ld=mold
    • Install with PREFIX set (for example sudo PREFIX=/usr ./install-mold.sh) to match your system layout
    • Read the author's paper on the design for details on how the speed is achieved

Downloads

Source code (.zip)main branch · straight from GitHubRelease v3.0.08 files incl. mold-3.0.0-ppc64le-linux.tar.gz

Strengths

  • The README reports large speedups over lld and wild in its own benchmarks, with the full inputs published on Zenodo
  • It is a drop-in replacement, so it works through existing compiler flags such as -fuse-ld=mold
  • It supports many CPU architectures and is MIT-licensed

Trade-offs

  • Benchmark results come from the author and were run on two specific machines, so your gains may differ
  • Some competitors cannot link certain programs (marked N/A), which makes direct comparison incomplete
  • Older GCC versions need a less convenient -B option to use it

Stats synced from GitHub. The assessment above was drafted with AI from the project's README on 2026-10-29 and may miss recent changes — check the README before relying on a command. MIT licence: free to use, modify and distribute, including commercially, as long as you keep the copyright notice.