The -l flag of compile isn't documented at https://golang.org/cmd/compile/. Additionally, the -N (no optimizations) flag doesn't disable inlining, which could lead one to believe that there is no way of disabling inlining.

The documentation does say

There are also a number of debugging flags; run the command with no arguments for a usage message

however disabling inlining should fall into the same category of flags as -N, which is documented there.