You can use:
llc -mcpu=help
to check the available options for your cpu target.
For example, I get:
$ llc -mcpu=help
Available CPUs for this target:
amdfam10 - Select the amdfam10 processor.
athlon - Select the athlon processor.
athlon-4 - Select the athlon-4 processor.
athlon-fx - Select the athlon-fx processor.
athlon-mp - Select the athlon-mp processor.
athlon-tbird - Select the athlon-tbird processor.
athlon-xp - Select the athlon-xp processor.
athlon64 - Select the athlon64 processor.
athlon64-sse3 - Select the athlon64-sse3 processor.
atom - Select the atom processor.
barcelona - Select the barcelona processor.
bdver1 - Select the bdver1 processor.
bdver2 - Select the bdver2 processor.
bdver3 - Select the bdver3 processor.
bdver4 - Select the bdver4 processor.
bonnell - Select the bonnell processor.
broadwell - Select the broadwell processor.
btver1 - Select the btver1 processor.
btver2 - Select the btver2 processor.
c3 - Select the c3 processor.
c3-2 - Select the c3-2 processor.
cannonlake - Select the cannonlake processor.
core-avx-i - Select the core-avx-i processor.
core-avx2 - Select the core-avx2 processor.
core2 - Select the core2 processor.
corei7 - Select the corei7 processor.
corei7-avx - Select the corei7-avx processor.
generic - Select the generic processor.
geode - Select the geode processor.
goldmont - Select the goldmont processor.
goldmont-plus - Select the goldmont-plus processor.
haswell - Select the haswell processor.
i386 - Select the i386 processor.
i486 - Select the i486 processor.
i586 - Select the i586 processor.
i686 - Select the i686 processor.
icelake-client - Select the icelake-client processor.
icelake-server - Select the icelake-server processor.
ivybridge - Select the ivybridge processor.
k6 - Select the k6 processor.
k6-2 - Select the k6-2 processor.
k6-3 - Select the k6-3 processor.
k8 - Select the k8 processor.
k8-sse3 - Select the k8-sse3 processor.
knl - Select the knl processor.
knm - Select the knm processor.
lakemont - Select the lakemont processor.
nehalem - Select the nehalem processor.
nocona - Select the nocona processor.
opteron - Select the opteron processor.
opteron-sse3 - Select the opteron-sse3 processor.
penryn - Select the penryn processor.
pentium - Select the pentium processor.
pentium-m - Select the pentium-m processor.
pentium-mmx - Select the pentium-mmx processor.
pentium2 - Select the pentium2 processor.
pentium3 - Select the pentium3 processor.
pentium3m - Select the pentium3m processor.
pentium4 - Select the pentium4 processor.
pentium4m - Select the pentium4m processor.
pentiumpro - Select the pentiumpro processor.
prescott - Select the prescott processor.
sandybridge - Select the sandybridge processor.
silvermont - Select the silvermont processor.
skx - Select the skx processor.
skylake - Select the skylake processor.
skylake-avx512 - Select the skylake-avx512 processor.
slm - Select the slm processor.
tremont - Select the tremont processor.
westmere - Select the westmere processor.
winchip-c6 - Select the winchip-c6 processor.
winchip2 - Select the winchip2 processor.
x86-64 - Select the x86-64 processor.
yonah - Select the yonah processor.
znver1 - Select the znver1 processor.
on my Intel® Xeon® Platinum 8163 cpu.
Though you still need to choose one from the list by yourself … Which requires you to have some knowledge on the cpu architecture.
Frequently used options are “core-avx2”, “skylake-avx512”.