diff --git a/devel/boost-all/compiled.mk b/devel/boost-all/compiled.mk
index 6062ce1d7666..c81c2a006e58 100644
--- a/devel/boost-all/compiled.mk
+++ b/devel/boost-all/compiled.mk
@@ -1,61 +1,62 @@
 USE_LDCONFIG=	yes
 PKGMESSAGE=	${WRKDIR}/pkg-message
 MAKE_CMD?=	bjam
 MAKEFILE=	#
 MAKE_FLAGS=	#
 ALL_TARGET=	stage
 #USES+=		compiler:c++17-lang
 USE_CXXSTD=	gnu++17
 
 PLIST_SUB+=	BOOST_MAJOR_VER=${BOOST_MAJOR_VER} \
 		BOOST_MINOR_VER=${BOOST_MINOR_VER} \
 		BOOST_SHARED_LIB_VER=${BOOST_SHARED_LIB_VER}
 
 PKG_MESSAGE_FILE_THREADS=	${PORTSDIR}/devel/boost-all/pkg-message.threads
 PKG_MESSAGE_FILE_PYTHON=	${PORTSDIR}/devel/boost-all/pkg-message.python
 
 MAKE_ARGS=	--layout=system \
 		--prefix=${PREFIX} \
 		-d2
 
 # Our compiler-flags will be added AFTER those set by bjam. We remove
 # the optimization level, because Boost sets it itself (to -O3 in case
 # of gcc/g++):
 MAKE_ARGS+=	cxxflags="${CXXFLAGS:N-O*}" cflags="${CFLAGS:N-O*}"
 
 MAKE_ARGS+=	--toolset=${CHOSEN_COMPILER_TYPE} \
 		${_MAKE_JOBS}
 
 DEBUG_MAKE_ARGS=	debug
 DEBUG_MAKE_ARGS_OFF=	release
 
 MAKE_ARGS+=	threading=multi \
 		link=shared,static
 
 MAKE_ARGS+=	optimization=speed
 OPTIMIZED_CFLAGS_MAKE_ARGS=	inlining=full
 
 # ccache build fails when using precompiled headers, on a cached build.
 #
 # base gcc 4.2.1 fails when using precompiled headers on 11.0+ kernel.
 # https://lists.freebsd.org/pipermail/svn-src-all/2015-March/101722.html
 MAKE_ARGS+=	pch=off
 
 .include <bsd.port.options.mk>
 
 .if ${OPSYS} == FreeBSD && \
 	((${OSVERSION} >= 1500000 && ${OSVERSION} < 1500017) || \
-	(${OSVERSION} >= 1400000 && ${OSVERSION} < 1400509) || \
-	(${OSVERSION} >= 1300000 && ${OSVERSION} < 1303502))
+	(${OSVERSION} >= 1400000 && ${OSVERSION} < 1400097)|| \
+	(${OSVERSION} >= 1300000 && ${OSVERSION} < 1300137) || \
+	${PORT_OPTIONS:MLLVM_FROM_PORTS})
 USES+=	llvm:build
 CHOSEN_COMPILER_TYPE=	clang
 .else
 USES+=	compiler:c++17-lang
 .endif
 
 post-patch:
 .if defined(USE_BINUTILS)
 	@${ECHO} "using ${CHOSEN_COMPILER_TYPE} : : ${CXX} : <linkflags>-B${LOCALBASE}/bin ;" >> ${WRKSRC}/tools/build/src/user-config.jam
 .else
 	@${ECHO} "using ${CHOSEN_COMPILER_TYPE} : : ${CXX} ;" >> ${WRKSRC}/tools/build/src/user-config.jam
 .endif
diff --git a/devel/boost-libs/Makefile b/devel/boost-libs/Makefile
index 5ce2aa66d57f..34abe110d84d 100644
--- a/devel/boost-libs/Makefile
+++ b/devel/boost-libs/Makefile
@@ -1,62 +1,84 @@
 PORTNAME=	boost-libs
 PORTREVISION?=	0
 
 COMMENT=	Free portable C++ libraries (without Boost.Python)
 WWW=		https://www.boost.org/
 
 LICENSE=	BSL
 LICENSE_FILE=	${WRKSRC}/LICENSE_1_0.txt
 
 BROKEN_sparc64=	https://github.com/boostorg/context/commit/f2ef6326b6ed
 
 BUILD_DEPENDS+=	bjam:devel/boost-jam
 
-OPTIONS_DEFINE=		DEBUG OPTIMIZED_CFLAGS
+# Note about LLVM_FROM_PORTS option:
+# Build of this port fails with assertion failure of compiler due to
+# bug of LLVM/Clang in base system. The failure happens when all of
+# following conditions are satisfied.
+# * OSVERSION is included in either of following ranges.
+#   1. 1500000 <= OSVERSION < 1500017
+#   2. 1400000 <= OSVERSION < 1400509
+#   3. 1300000 <= OSVERSION < 1303502
+# * Base system is built with WITH_LLVM_ASSERTIONS variable set.
+# So if your base system fulfills them you need to use LLVM ports to
+# build this port.
+# By default WITH_LLVM_ASSERTIONS variable is set with -CURRENT but
+# not with -STABLE and -RELEASE. So whereas most -CURRENT users face
+# the build failure, few -STABLE and -RELEASE user faces it.
+# Therefore by default this port uses LLVM from ports only if base
+# system is -CURRENT and OSVERSION is included in above ranges. It
+# make it possible for most -STABLE and -RELEASE users to avoid to
+# build LLVM ports unnecessarily. But if someone uses -STABLE or
+# -RELEASE built with WITH_LLVM_ASSERTIONS set, then he can't build
+# this port successfully on such system. So provide LLVM_FROM_PORTS
+# option as a last resort for him.
+OPTIONS_DEFINE=		DEBUG LLVM_FROM_PORTS OPTIMIZED_CFLAGS
 OPTIONS_MULTI=		LOCALE
 OPTIONS_MULTI_LOCALE=	ICONV ICU
 OPTIONS_DEFAULT=	ICONV ICU
 ICONV_DESC=		Boost.Locale with iconv encoding support
 ICU_DESC=		Boost.Regex/Locale with ICU unicode support
+LLVM_FROM_PORTS_DESC=	Use LLVM from ports to build
 
 ICONV_USES=		iconv
 ICONV_MAKE_ARGS=	-sICONV_PATH=${ICONV_PREFIX}
 ICONV_MAKE_ARGS_OFF=	boost.locale.iconv=off
 ICU_LIB_DEPENDS=	libicuuc.so:devel/icu
 ICU_MAKE_ARGS=		-sICU_PATH=${LOCALBASE}
 ICU_MAKE_ARGS_OFF=	boost.locale.icu=off
 
 .include "${.CURDIR}/../boost-all/common.mk"
 
 .include "${.CURDIR}/../boost-all/compiled.mk"
 
 MAKE_ARGS+=	--without-python
 MAKE_ARGS+=	${MAKE_ARGS_${CHOSEN_COMPILER_TYPE}}
 MAKE_ARGS_gcc=	xdll-path=${_GCC_RUNTIME}
 ALL_TARGET=	stage
 
 .include <bsd.port.options.mk>
 
 do-install:
 	@cd ${WRKSRC} && ${SETENV} ${MAKE_ENV} ${MAKE_CMD} \
 		${MAKE_ARGS:NDESTDIR=*:S,^--prefix=,&${STAGEDIR},} ${INSTALL_TARGET}
 	@${FIND} ${STAGEDIR}${PREFIX}/lib/cmake -type f -exec \
 		${REINPLACE_CMD} -i '' -e 's,${STAGEDIR},,' {} +
 # For some reasons BJAM forget about the links
 	@cd ${WRKSRC}/stage/ && ${FIND} lib -type l | ${PAX} -rw -p p ${STAGEDIR}${PREFIX}
 
 # display pkg-message
 post-install:
 	@${TOUCH} ${PKGMESSAGE}
 
 	@${CAT} ${PKG_MESSAGE_FILE_THREADS} >> ${PKGMESSAGE}
 	@${ECHO_CMD} >> ${PKGMESSAGE}
 
 	@${STRIP_CMD} ${STAGEDIR}${PREFIX}/lib/*.so
 
 	@${REINPLACE_CMD} \
 		-e "s|%%LOCALBASE%%|${LOCALBASE}|g" \
 		-e "s|%%PYTHON_INCLUDEDIR%%|${PYTHON_INCLUDEDIR}|g" \
 		-e "s|%%PYTHON_LIBDIR%%|${PYTHON_LIBDIR}|g" \
 		-e "s|%%PYTHON_VERSION%%|${PYTHON_VERSION}|g" ${PKGMESSAGE}
 
 .include <bsd.port.mk>