diff --git a/Mk/Uses/llvm.mk b/Mk/Uses/llvm.mk
index 6fa1f60c5d41..2cae756fd280 100644
--- a/Mk/Uses/llvm.mk
+++ b/Mk/Uses/llvm.mk
@@ -1,102 +1,118 @@
 # Provides support to depend on LLVM
 #
-# It chooses the llvm port to be used based on the following constraint:
-#	1) no constraints given						=> ${LLVM_DEFAULT}
-#	2) exact constraint given					=> ${exact}
-#	2) max constraint given && ${max} < ${LLVM_DEFAULT}		=> ${max}
-#	3) min constraint given && ${LLVM_DEFAULT} < ${LLVM_DEFAULT}	=> ${LLVM_DEFAULT}
-
-# Usage:
-# 	USES=	llvm			- default version chosen
-# 	USES=	llvm:15			- exact constraint
-# 	USES=	llvm:min=9		- min constraint: max(min,default)
-# 	USES=	llvm:max=10		- max constraint: min(max,default)
-# 	USES=	llvm:min=10,max=11	- all constraint: max(min(max,default),default)
+# USES=llvm supports two kinds of arguments:
+#
+# * mode
+#         <none>:         defaults to build
+#         build:          add a BUILD_DEPENDS on chosen llvm-port
+#         run:            add a RUN_DEPENDS on chosen llvm-port
+#         lib:            add a LIB_DEPENDS on chosen llvm-port
+#
+# * version
+#         <none>:         defaults to ${LLVM_DEFAULT}
+#         number:         use explicitly the specified version
+#         min=number:     use specified min if ${LLVM_DEFAULT} is lower
+#         max=number:     use specified max if ${LLVM_DEFAULT} is higher
+#
+# An example usage might be:
+#         USES=   llvm
+#   or
+#         USES=   llvm:13,build
+#   or
+#         USES=   llvm:min=14,lib
+#
+# The following variables are exposed to be used in the ports tree at the moment:
+#         * LLVM_VERSION  version chosen from the arguments to llvm.mk
+#         * LLVM_PORT     chosen llvm port
+#         * LLVM_CONFIG   llvm-config of the chosen port
+#         * LLVM_LIBLLVM  libLLVM.so of the chosen port
+#         * LLVM_PREFIX   installation prefix of the chosen port
+#
 
 .if !defined(_INCLUDE_USES_LLVM_MK)
 _INCLUDE_USES_LLVM_MK=	YES
 
 _LLVM_MK_VALID_VERSIONS=	7 8 9 10 11 12 13 14 15
 _LLVM_MK_VALID_CONSTRAINTS=	min max
 _LLVM_MK_VALID_MODES=		build run lib
 
 # === parse mode arguments ===
 _LLVM_MK_MODES=	# empty
 .  for _mode in ${_LLVM_MK_VALID_MODES}
 .    if ${llvm_ARGS:M${_mode}}
 _LLVM_MK_MODES+=	${_mode}
 .    endif
 .  endfor
 .  if empty(_LLVM_MK_MODES)
 _LLVM_MK_MODES=	build
 .  endif
 
 # === parse version arguments ===
 _LLVM_MK_VERSION=	# empty
 .  for _ver in ${_LLVM_MK_VALID_VERSIONS}
 .    if ${llvm_ARGS:M${_ver}}
 .      if !empty(_LLVM_MK_VERSION)
 BROKEN=		USES=llvm:${llvm_ARGS} contains multiple version definitions
 .      else
 _LLVM_MK_VERSION=	${_ver}
 .      endif
 .    endif
 .  endfor
 .  if empty(_LLVM_MK_VERSION)
 .    if ${LLVM_DEFAULT:N1[0-9]*}
 _LLVM_MK_VERSION=	${LLVM_DEFAULT:S/0$//}
 .    else
 _LLVM_MK_VERSION=	${LLVM_DEFAULT}
 .    endif
 .  endif
 
 # === handle constraints ===
 .  for _constraint in ${_LLVM_MK_VALID_CONSTRAINTS}
 _version=	${llvm_ARGS:M${_constraint}=[0-9]*:S/${_constraint}=//}
 .    if !empty(_version)
 _LLVM_MK_CONSTRAINT_${_constraint}=	${_version}
 .    endif
 .  endfor
 
 .  if !empty(_LLVM_MK_CONSTRAINT_min)
 .    if ${_LLVM_MK_CONSTRAINT_min} > ${_LLVM_MK_VERSION}
 _LLVM_MK_VERSION=	${_LLVM_MK_CONSTRAINT_min}
 .    endif
 .  endif
 
 .  if !empty(_LLVM_MK_CONSTRAINT_max)
 .    if ${_LLVM_MK_CONSTRAINT_max} < ${_LLVM_MK_VERSION}
 _LLVM_MK_VERSION=	${_LLVM_MK_CONSTRAINT_max}
 .    endif
 .  endif
 
 # === define helpers for the dependencies ===
 .  for _ver in ${_LLVM_MK_VALID_VERSIONS:N1[0-9]}
 _LLVM_MK_SUFFIX_${_ver}=	${_ver}0
 .  endfor
 
 .  for _ver in ${_LLVM_MK_VALID_VERSIONS}
 _LLVM_MK_SUFFIX_${_ver}?=	${_ver}
 .  endfor
 
 # === define variables to depend on and export ===
 _LLVM_MK_PORT=		devel/llvm${_LLVM_MK_SUFFIX_${_LLVM_MK_VERSION}}
 _LLVM_MK_LIBLLVM=	libLLVM-${_LLVM_MK_VERSION}.so
 _LLVM_MK_PATH=		llvm-config${_LLVM_MK_SUFFIX_${_LLVM_MK_VERSION}}
 _LLVM_MK_PREFIX=	${PREFIX}/llvm${_LLVM_MK_SUFFIX_${_LLVM_MK_VERSION}}
 
 # == add actual dependencies ===
 _LLVM_MK_PATH_lib=	${_LLVM_MK_LIBLLVM}
 .  for _mode in ${_LLVM_MK_MODES}
 _LLVM_MK_PATH_${_mode}?=	${_LLVM_MK_PATH}
 ${_mode:tu}_DEPENDS+=	${_LLVM_MK_PATH_${_mode}}:${_LLVM_MK_PORT}
 .  endfor
 
 # == export config ===
 LLVM_PORT=		${_LLVM_MK_PORT}
 LLVM_CONFIG=		${_LLVM_MK_PATH}
 LLVM_LIBLLVM=		${_LLVM_MK_LIBLLVM}
 LLVM_VERSION=		${_LLVM_MK_VERSION}
 LLVM_PREFIX=		${_LLVM_MK_PREFIX}
 
 .endif