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rui314
mold
Rust2020–2026
rui314 / mold

mold

mold 🦠: A Modern Linker in Rust 🦀

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REPOSITORY AT A GLANCE

What to know before exploring

What it is

mold 🦠: A Modern Linker in Rust 🦀

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

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Also in these discussions

Mentioned in the same Hacker News threads. That is not proof they are substitutes.

This week on Hacker News

Nov 8–Nov 15 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/15/2026, 10:01:16 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year95 dated mentions

Observed mentions: 2020-12-13 19:21:00 UTC to 2026-10-05 20:22:21 UTC.

01020302020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 2 mentions; 1 submissions, 1 comments20202021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 15 mentions; 7 submissions, 8 comments2022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 34 mentions; 8 submissions, 26 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 20 mentions; 4 submissions, 16 comments20232024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 9 mentions; 5 submissions, 4 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 8 mentions; 1 submissions, 7 comments2026-01-01 00:00:00 UTC to 2027-01-01 00:00:00 UTC (exclusive): 7 mentions; 2 submissions, 5 comments. Incomplete calendar period.2026*

* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

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PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC211
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC1578
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC34826
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC20416
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC954
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC817
2026 (partial)2026-01-01 00:00:00 UTC2027-01-01 00:00:00 UTC725

From the project README

An excerpt from the repository, fetched Nov 13, 2026.

Read the project’s introduction
mold: A Modern Linker mold is a high-performance drop-in replacement for existing Unix linkers, designed to speed up builds. In our August 2026 benchmarks, it links 4.9x faster than LLVM lld and 1.9x faster than wild at the median; see Benchmark for the full results. mold is written by the original developer of LLVM lld, the linker that Android, Chrome, FreeBSD, PlayStation, Nintendo Switch, and other production systems are built with. mold started as an effort to build an even faster linker from scratch, free of the architectural limits its author had run into while optimizing lld. It has been in production use since 2021, and today it is the default linker of many large open-source projects and is used internally by many companies. mold supports x86-64, i386, ARM 32/64, RISC-V 32/64, PowerPC 32/64, s390x, LoongArch 32/64, SPARC64, m68k, and SH-4. Why does linking speed matter? If you are using a compiled language such as C, C++, or Rust, a build consists of two phases. In the first phase, a compiler compiles source files into object files (.o files). In the second phase, a linker takes all object files and combines them into a single executable or shared library file. The second phase can be time-consuming if your build output is large. mold can speed up this process, saving you time and preventing distractions while waiting for a lengthy build to finish. The difference is most noticeable during rapid debug-edit-rebuild cycles. Benchmark Here is a performance comparison of lld, wild, and mold when linking nine large programs on two machines: AMD Ryzen Threadripper 7980X (64 cores) running Ubuntu 24.04 Apple M1 Ultra (16 performance cores and 4 efficiency cores) running Fedora Asahi Remix 42; the benchmark is restricted to the performance cores The Threadripper represents many-core workstation and server processors, and the M1 Ultra represents high-performance desktop processors. All three linkers were built from source in release configuration as of 2026-08-28 and ran with their default options. Times are wall-clock times as seen by the caller, the median of three runs after a warm-up. The ARM64 rows are the ARM64 builds of the same programs. The benchmark suite, including all linker inputs, is available on Zenodo. AMD Ryzen Threadripper 7980X, debug builds Program (output size) lld wild mold wild/mold lld/mold Blender 5.2 (2.46 GiB) 4.72s 1.98s 0.86s 2.3x 5.5x Chromium 145 (4.51 GiB) 16.64s 3.98s 1.65s 2.4x 10.1x Chromium 145 ARM64 (4.76 GiB) 20.91s N/A 1.83s N/A 11.4x Clang 21 (4.19 GiB) 6.19s 3.71s 1.34s 2.8x 4.6x ClickHouse 26.1 (5.58 GiB) 6.62s 4.40s 0.98s 4.5x 6.7x Firefox 149 (2.37 GiB) 5.11s N/A 0.78s N/A 6.5x Firefox 149 ARM64 (2.43 GiB) 6.40s N/A 0.93s N/A 6.9x Godot 4.6 (1.01 GiB) 1.77s 1.08s 0.46s 2.3x 3.8x LibreOffice 26.2 (0.98 GiB) 3.46s 1.41s 0.44s 3.2x 7.9x PyTorch 2.9 (3.51 GiB) 4.35s 2.48s 0.80s 3.1x 5.4x TensorFlow 2.21 (9.55 GiB) 50.73s N/A 3.15s N/A 16.1x AMD Ryzen Threadripper 7980X, release builds Program (output size) lld wild mold wild/mold lld/mold Blender 5.2 (0.24 GiB) 0.85s 0.30s 0.20s 1.5x 4.2x Chromium 145 (0.58 GiB) 6.48s N/A 0.64s N/A 10.2x Chromium 145 ARM64 (0.60 GiB) 7.91s N/A 0.73s N/A 10.8x Clang 21 (0.21 GiB) 0.53s 0.23s 0.11s 2.2x 5.0x ClickHouse 26.1 (1.23 GiB) 3.18s 2.07s 0.41s 5.0x 7.7x Firefox 149 (0.22 GiB) 1.01s 0.41s 0.21s 2.0x 4.9x Godot 4.6 (0.15 GiB) 0.44s 0.21s 0.08s 2.7x 5.8x LibreOffice 26.2 (0.19 GiB) 1.13s 0.57s 0.19s 3.0x 6.0x PyTorch 2.9 (0.31 GiB) 0.68s 0.32s 0.15s 2.2x 4.7x TensorFlow 2.21 (0.73 GiB) 9.62s N/A 0.70s N/A 13.7x Apple M1 Ultra, debug builds Program (output size) lld wild mold wild/mold lld/mold Blender 5.2 (2.46 GiB) 3.21s 1.81s 1.56s 1.2x 2.1x Chromium 145 (4.51 GiB) 9.54s 3.49s 2.22s 1.6x 4.3x Chromium 145 ARM64 (4.76 GiB) 12.67s N/A 2.31s N/A 5.5x Clang 21 (4.19 GiB) 4.40s 2.78s 2.96s 0.9x 1.5x ClickHouse 26.1 (5.58 GiB) 4.92s 3.50s 1.71s 2.1x 2.9x Firefox 149 (2.37 GiB) 3.21s N/A 1.12s N/A 2.9x Firefox 149 ARM64 (2.43 GiB) 4.13s N/A 1.12s N/A 3.7x Godot 4.6 (1.01 GiB) 1.12s 0.81s 0.62s 1.3x 1.8x LibreOffice 26.2 (0.98 GiB) 2.08s 0.94s 0.63s 1.5x 3.3x PyTorch 2.9 (3.51 GiB) 3.07s 2.10s 1.45s 1.4x 2.1x TensorFlow 2.21 (9.55 GiB) 43.68s N/A 4.43s N/A 9.9x Apple M1 Ultra, release builds Program (output size) lld wild mold wild/mold lld/mold Blender 5.2 (0.24 GiB) 0.56s 0.20s 0.25s 0.8x 2.3x Chromium 145 (0.58 GiB) 4.25s N/A 0.78s N/A 5.5x Chromium 145 ARM64 (0.60 GiB) 5.17s N/A 0.91s N/A 5.7x Clang 21 (0.21 GiB) 0.30s 0.15s 0.14s 1.0x 2.1x ClickHouse 26.1 (1.23 GiB) 1.94s 0.95s 0.55s 1.7x 3.5x Firefox 149 (0.22 GiB) 0.56s 0.23s 0.20s 1.1x 2.7x Godot 4.6 (0.15 GiB) 0.26s 0.11s 0.11s 1.0x 2.3x LibreOffice 26.2 (0.19 GiB) 0.62s 0.30s 0.23s 1.3x 2.7x PyTorch 2.9 (0.31 GiB) 0.43s 0.22s 0.17s 1.3x 2.5x TensorFlow 2.21 (0.73 GiB) 8.07s N/A 0.68s N/A 11.9x N/A indicates that the linker cannot link that program. wild's Chromium release links are also marked N/A because wild does not implement --icf=all and links without identical code folding. Why is mold so fast? mold owes its speed to pervasive parallelism and to efficient data structures and algorithms. For details, read our paper "mold: A Massively Parallel Linker" (ASPLOS 2027), available at https://arxiv.org/abs/2608.23228. Installation Binary packages for the following systems are currently available: Prebuilt binaries for Linux on x86-64, ARM64, ARM32, RISC-V, PPC64LE, s390x, and LoongArch are also attached to each GitHub release. How to Build mold is written in Rust and built with Cargo. It requires Rust 1.95 or later; if your system's Rust is older, install the stable toolchain with rustup. You also need Git and a C compiler such as GCC or Clang, which you can install with your system's package manager. Compile mold git clone https://github.com/rui314/mold.git cd mold cargo build --release The executable is target/release/mold. Install mold Run
Read the full README on GitHub

What Hacker News says

20 sources
inkyoto·Dec 31, 2023
Oh, yes, you are. The optimising steps, linking and the link-time optimisation (LTO) are very heavily memory bound, especially on large codebases. The Rust compiler routinely hits the 45-50Gb/sec ballpark of the intra-memory transfer speed on compiling a medium sized project, more if the code base large. Haskell (granted, a fringe yet revealing case) case just as routinely hits the 60-70 Gb/sec memory transfer speed at the compile time, and large to very large C++ codebases add a lot of stress on the memory at the optimisation step. If I am not mistaken, Go is also very memory bound. Then there comes the linking and particularly the LTO that want all the memory bandwidth they can get to get the job done quickly, and the memory speed becomes a major bottleneck. Loading the entire codebase into memory, in fact, the major optimisation techni
Read the rest
que used in mold[0] that can vastly benefit from a) faster memory, b) a wider memory bus. [0] https://github.com/rui314/mold
In Tracking developer build times to decide if the M3 MacBook is worth upgrading
zX41ZdbW·Jul 26, 2023
I'm amazed at how quickly the author responds to requests: https://github.com/rui314/mold/issues/1057 From the report to the fix in less than two days. I'm not sure how competitive it will be with lld, especially if we consider ThinLTO (which takes multiple minutes on 64-core machine) - it can make the advantages of mold insignificant.
In Mold 2.0
hgs3·Jul 26, 2023
> it wasn't worth the hassle If selling licenses is a hassle, then that indicates a problem with the open source ecosystem as GitHub and other code hosting websites should offer monetization tools for selling closed-source licenses directly from their web interface. I'm talking legal forms, templates, payment processors, and product tracking. Selling licenses should be easy, not a hassle. [1] https://github.com/rui314/mold/releases/tag/v2.0.0
In Mold 2.0
conradev·Jun 7, 2023
The problem is not Apple-specific and their solution could be useful elsewhere. The specific optimization this achieves is during build time only: these new files are static libraries that are quicker to link. It is a small shift of some of the linking pipeline into the (parallel) builds of dependent libraries, rather than heaping it all onto the linker at the end of the build. The linker has to essentially re-link from scratch for every small change. Parallelization has long been known as the best way to speed up linking. This Apple change comes in addition to rewriting their linker to be massively parallel. Mold did it first, though: https://github.com/rui314/mold edit: lld did it first, mold improved upon it A faster development cycle is one of the coolest improvements that Zig brings – lightning fast recompiles, bringing the native de
Read the rest
velopment cycle closer to web speed. More languages should get this capability, and Apple needs it for Swift to get instantly updating SwiftUI previews. Static linking is required to get the best performance: no linker runtime cost, cross-language LTO and dead code elimination If this optimization is generally applicable and developers find it worthwhile, I could imagine this making its way to GCC-land. At the very least, gold needs replacing/rewriting to be competitive now. edited: for clarity
In Mergeable libraries [video]

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