mold is a high-performance linker that serves as a drop-in replacement for existing Unix linkers like GNU ld and LLVM lld.
The tool addresses the problem that linking can become a significant bottleneck in build times, particularly for large C, C++, and Rust projects during rapid debug-edit-rebuild cycles. mold achieves its speed through a ground-up redesign that avoids architectural limitations present in earlier linkers. Written by the original developer of LLVM lld, it incorporates lessons learned from optimizing that linker while being built without those legacy constraints. The tool supports a wide range of architectures including x86-64, ARM 32/64, RISC-V, PowerPC, s390x, LoongArch, SPARC64, m68k, and SH-4.
Developers should consider mold if they work with large compiled codebases where linking time noticeably impacts iteration speed. It functions as a direct replacement for standard linkers, requiring minimal integration effort. The tool has been in production use since 2021 and serves as the default linker for numerous large open-source projects and companies. Compared to LLVM lld, the README demonstrates substantially faster linking times across large real-world programs; compared to wild, another modern linker, mold shows consistent performance advantages.
The project maintains active development with regular updates to support new architectures and handle edge cases discovered in production use. The maintainer responds to issues and pull requests, indicating ongoing engagement with the user base. The codebase receives improvements addressing both performance optimization and compatibility across diverse platforms. Documentation includes detailed benchmarking methodology and reproducible test cases, reflecting a commitment to transparent performance claims.
