Throttling Building LLVM

Kaspar Winckler · August 27, 2026 at 5:59 PM

Hello,

I am building packages that require LLVM, and building LLVM either hangs (LE 12) or bails out (LE 13).

This occurs because my system does not have enough RAM and swap space for building LLVM with the default thread count.

I would prefer not to increase RAM or swap space.

Is there a variable I can add to the build command to limit the number of threads used during build?

I am certain there is one, but it rolled out of my command cache, and I can't find one in the code or in this forum.

Thank you in advance for any help with this.

**HiassofT** · August 27, 2026 at 6:18 PM

Set the THREADCOUNT environment variable.

As a rule of thumb building LLVM needs about 1GB RAM per thread.

so long,

Hias

Kaspar Winckler · August 27, 2026 at 11:21 PM

Thank you for the answer, but THREADCOUNT has no effect on Ninja.

Throwing it back here for anyone who needs it.