diff --git a/.github/workflows/crossdev.yml b/.github/workflows/crossdev.yml
index f74cf03..fd03d1c 100644
--- a/.github/workflows/crossdev.yml
+++ b/.github/workflows/crossdev.yml
@@ -18,63 +18,147 @@ jobs:
         # requests fixing them welcome!
         target:
           - target: aarch64-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: aarch64-unknown-linux-musl
+            gcc: true
+            llvm: true
           - target: aarch64_be-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: alpha-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: arm-unknown-linux-gnueabi
+            gcc: true
+            llvm: false
           - target: arm-unknown-linux-gnueabihf
+            gcc: true
+            llvm: false
           - target: arm-unknown-linux-musleabi
+            gcc: true
+            llvm: false
           - target: arm-unknown-linux-musleabihf
+            gcc: true
+            llvm: false
           - target: armeb-unknown-linux-gnueabi
+            gcc: true
+            llvm: false
           - target: armeb-unknown-linux-gnueabihf
+            gcc: true
+            llvm: false
           - target: armeb-unknown-linux-musleabi
+            gcc: true
+            llvm: false
           - target: armeb-unknown-linux-musleabihf
+            gcc: true
+            llvm: false
           - target: armv7-unknown-linux-musleabi
+            gcc: true
+            llvm: false
           - target: armv7-unknown-linux-musleabihf
+            gcc: true
+            llvm: false
           - target: armv6j-softfp-linux-gnueabi
+            gcc: true
+            llvm: false
           - target: armv6j-unknown-linux-gnueabihf
+            gcc: true
+            llvm: false
           - target: armv7a-softfp-linux-gnueabi
+            gcc: true
+            llvm: false
           - target: armv7a-unknown-linux-gnueabihf
+            gcc: true
+            llvm: false
           - target: hppa1.1-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: hppa2.0-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: hppa64-unknown-linux-gnu
             args: --skip-system
+            gcc: true
+            llvm: false
           - target: loongarch64-unknown-linux-gnu
+            gcc: true
+            llvm: false
           # musl ebuilds don't support loong. The target is supported upstream,
           # we need to fix and test our ebuilds.
           #- target: loongarch64-unknown-linux-musl
           - target: m68k-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: mips-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: mips-unknown-linux-musl
+            gcc: true
+            llvm: false
           - target: mipsel-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: mipsel-unknown-linux-musl
+            gcc: true
+            llvm: false
           - target: mips64-unknown-linux-gnu
+            gcc: true
+            llvm: false
           # libgcc_s.so fails to build: `cannot find crti.o: No such file or
           # directory`.
           # - target: mips64-unknown-linux-musl
           - target: mips64el-unknown-linux-gnu
+            gcc: true
+            llvm: false
           # libgcc_s.so fails to build: `cannot find crti.o: No such file or
           # directory`.
           # - target: mips64el-unknown-linux-musl
           - target: or1k-unknown-linux-gnu
             args: --skip-system
+            gcc: true
+            llvm: false
           - target: or1k-unknown-linux-musl
             args: --skip-system
+            gcc: true
+            llvm: false
           - target: powerpc-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: powerpc-unknown-linux-musl
+            gcc: true
+            llvm: false
           - target: powerpc64-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: powerpc64-unknown-linux-musl
+            gcc: true
+            llvm: false
           - target: powerpc64le-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: riscv32-unknown-linux-gnu
+            gcc: true
+            llvm: false
           # busybox fails to build: `‘SYS_settimeofday’ undeclared`.
           # - target: riscv32-unknown-linux-musl
           - target: riscv64-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: riscv64-unknown-linux-musl
+            gcc: true
+            llvm: true
           # glibc fails to build: `no support for pre-v8 sparc`.
           # - target: sparc-unknown-linux-gnu
           - target: sparc64-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: s390-ibm-linux-gnu
+            gcc: true
+            llvm: false
           - target: s390x-ibm-linux-gnu
+            gcc: true
+            llvm: false
           # musl ebuilds don't support s390x. The target is supported upstream,
           # we need to fix and test our ebuilds.
           # - target: s390x-unknown-linux-musl
@@ -89,30 +173,58 @@ jobs:
           # - target: sh4eb-unknown-linux-gnu
           # - target: sh4eb-unknown-linux-musl
           - target: x86_64-unknown-linux-gnu
+            gcc: true
+            llvm: false
           - target: x86_64-unknown-linux-musl
+            gcc: true
+            llvm: true
           # Embedded or otherwise special targets
           - target: arm-none-eabi
             args: --skip-system
+            gcc: true
+            llvm: false
           - target: avr
             args: --skip-system
+            gcc: true
+            llvm: false
           - target: nvptx-none
             args: --skip-system
+            gcc: true
+            llvm: false
           - target: bpf-unknown-none
             args: --skip-system
+            gcc: true
+            llvm: false
         stage3:
-          - latest # `openrc` (glibc+GCC) is tagged as `latest`
-          - musl
+          - latest # glibc+GCC
+          - llvm # glibc+LLVM and GCC as a fallback
+          - musl # musl+GCC
       fail-fast: false
     name: crossdev target=${{ matrix.target.target }} stage3=${{ matrix.stage3 }}
+    env:
+      CONTAINER_ENGINE: docker
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
 
-      - name: Create cross environment
-        env:
-          CONTAINER_ENGINE: docker
+      - name: Create cross environment with GCC
+        # Building GCC-based sysroots on llvm stage3 should be possible, since
+        # it contains a fallback GCC toolchain. But in practice, it fails for
+        # certain architectures. Pull requests welcome!
+        if: ${{ matrix.target.gcc && !contains(matrix.stage3, 'llvm') }}
         run: |
           ./scripts/container_test.sh \
             --tag ${{ matrix.stage3 }} \
             --target ${{ matrix.target.target }} \
             ${{ matrix.target.args }}
+
+      - name: Create cross environment with LLVM
+        # * We need LLVM toolchain to be present in the stage3.
+        # * Building sysroots with glibc and LLVM is not yet supported.
+        if: ${{ matrix.target.llvm && contains(matrix.stage3, 'llvm') }}
+        run: |
+          ./scripts/container_test.sh \
+            --llvm \
+            --tag ${{ matrix.stage3 }} \
+            --target ${{ matrix.target.target }} \
+            ${{ matrix.target.args }}
diff --git a/crossdev b/crossdev
index fb03720..c3e0ead 100755
--- a/crossdev
+++ b/crossdev
@@ -906,6 +906,9 @@ KCAT="sys-kernel" ; KPKG="linux-headers" ; KVER="" KUSE="" KENV="" KOVL="" KMASK
 LCAT="sys-libs"   ; LPKG="[none]"        ; LVER="" LUSE="" LENV="" LOVL="" LMASK="" LFORCE=""
 DCAT="dev-debug"  ; DPKG="gdb"           ; DVER="" DUSE="" DENV="" DOVL="" DMASK="" DFORCE=""
 RCAT="llvm-runtimes" ; RPKG="compiler-rt"   ; RVER="" RUSE="" RENV="" ROVL="" RMASK="" RFORCE=""
+UCAT="llvm-runtimes" ; UPKG="libunwind"     ; UVER="" UUSE="" UENV="" UOVL="" UMASK="" UFORCE=""
+ACAT="llvm-runtimes" ; APKG="libcxxabi"     ; AVER="" AUSE="" AENV="" AOVL="" AMASK="" AFORCE=""
+PCAT="llvm-runtimes" ; PPKG="libcxx"        ; PVER="" PUSE="" PENV="" POVL="" PMASK="" PFORCE=""
 CCAT="sys-devel"  ; CPKG="clang-crossdev-wrappers" ; CVER="" CUSE="" CENV="" COVL="" CMASK="" CFORCE=""
 XPKGS=() XVERS=() XUSES=() XENVS=() XOVLS=() XMASKS=() XFORCES=()
 DEFAULT_VER="[latest]"
@@ -948,69 +951,84 @@ LLVM="no"
 
 while [[ $# -gt 0 ]] ; do
 	case $1 in
-	-V|--version)      echo "crossdev-${CROSSDEV_VER}"; exit 0;;
-	-t|--target)       shift; parse_target $1;;
-	--b|--binutils)    shift; BVER=$1;;
-	--benv)            shift; BENV=$1;;
-	-ob|--ov-binutils) shift; BOVL=$1;;
-	--bcat)            shift; BCAT=$1;;
-	--bpkg)            shift; BPKG=$1;;
-	--d|--gdb)         shift; DVER=$1;;
-	--denv)            shift; DENV=$1;;
-	-od|--ov-gdb)      shift; DOVL=$1;;
-	--dcat)            shift; DCAT=$1;;
-	--dpkg)            shift; DPKG=$1;;
-	--g|--gcc)         shift; GVER=$1;;
-	--genv)            shift; GENV=$1;;
-	-og|--ov-gcc)      shift; GOVL=$1;;
-	--gcat)            shift; GCAT=$1;;
-	--gpkg)            shift; GPKG=$1;;
-	--k|--kernel)      shift; KVER=$1;;
-	--kenv)            shift; KENV=$1;;
-	-ok|--ov-kernel)   shift; KOVL=$1;;
-	--kcat)            shift; KCAT=$1;;
-	--kpkg)            shift; KPKG=$1;;
-	--l|--libc)        shift; LVER=$1;;
-	--lenv)            shift; LENV=$1;;
-	-ol|--ov-libc)     shift; LOVL=$1;;
-	--lcat)            shift; LCAT=$1;;
-	--lpkg)            shift; LPKG=$1;;
-	--r|--crt)         shift; RVER=$1;;
-	--renv)            shift; RENV=$1;;
-	-or|--ov-crt)      shift; ROVL=$1;;
-	--rcat)            shift; RCAT=$1;;
-	--rpkg)            shift; RPKG=$1;;
-	--c|--ccw)         shift; CVER=$1;;
-	--cenv)            shift; CENV=$1;;
-	-oc|--ov-ccw)      shift; COVL=$1;;
-	--ccat)            shift; CCAT=$1;;
-	--cpkg)            shift; CPKG=$1;;
-	-ox|--ov-extra)    shift; XOVLS+=( "$1" );;
-	--env)             shift; AENV=$1;;
-	-L|--llvm)         LLVM="yes";;
-	-A|--abis)         shift; MULTILIB_ABIS=$1;;
-	--host-abi)        shift; HOST_ABI=$1;;
-	-S|--stable)       DEFAULT_VER="[stable]";;
-	-C|--clean)        shift; parse_target $1; ACTION="uninstall";;
-	-s?|--stage?)      STAGE=${1:0-1};;
-	-oS|--overlays)    shift; SEARCH_OVERLAYS=$1;;
-	-oO|--ov-output)   shift; CROSSDEV_OVERLAY=$1;;
-	--ex-only)         EX_FAST="yes";;
-	--ex-gcc)          EX_GCC="yes";;
-	--ex-gdb)          EX_GDB="yes";;
-	--ex-pkg)          shift; XPKGS+=( "$1" );;
-	--with-*)          eval $(set_withval $1);;
-	--without-*)       eval $(set_withval $1);;
-	-f|--force)        FORCE="yes";;
-	-x)                SET_X="yes";;
-	--show-target-cfg) SHOW_TARGET_CFG="yes";;
-	--init-target)     INIT_TARGET_ONLY="yes";;
-	--show-fail-log)   SHOW_FAIL_LOG="yes";;
-	--show-repo-cfg)   show_repo_cfg "$2";;
-	-P|--portage)      UOPTS="${UOPTS} $2"; shift;;
-	-h|--help)         usage;;
-	-*)                eerror "UNKNOWN OPTION: '$1'" ; usage 1;;
-	*)                 parse_target $1;;
+	-V|--version)        echo "crossdev-${CROSSDEV_VER}"; exit 0;;
+	-t|--target)         shift; parse_target $1;;
+	--b|--binutils)      shift; BVER=$1;;
+	--benv)              shift; BENV=$1;;
+	-ob|--ov-binutils)   shift; BOVL=$1;;
+	--bcat)              shift; BCAT=$1;;
+	--bpkg)              shift; BPKG=$1;;
+	--d|--gdb)           shift; DVER=$1;;
+	--denv)              shift; DENV=$1;;
+	-od|--ov-gdb)        shift; DOVL=$1;;
+	--dcat)              shift; DCAT=$1;;
+	--dpkg)              shift; DPKG=$1;;
+	--g|--gcc)           shift; GVER=$1;;
+	--genv)              shift; GENV=$1;;
+	-og|--ov-gcc)        shift; GOVL=$1;;
+	--gcat)              shift; GCAT=$1;;
+	--gpkg)              shift; GPKG=$1;;
+	--k|--kernel)        shift; KVER=$1;;
+	--kenv)              shift; KENV=$1;;
+	-ok|--ov-kernel)     shift; KOVL=$1;;
+	--kcat)              shift; KCAT=$1;;
+	--kpkg)              shift; KPKG=$1;;
+	--l|--libc)          shift; LVER=$1;;
+	--lenv)              shift; LENV=$1;;
+	-ol|--ov-libc)       shift; LOVL=$1;;
+	--lcat)              shift; LCAT=$1;;
+	--lpkg)              shift; LPKG=$1;;
+	--r|--crt)           shift; RVER=$1;;
+	--renv)              shift; RENV=$1;;
+	-or|--ov-crt)        shift; ROVL=$1;;
+	--rcat)              shift; RCAT=$1;;
+	--rpkg)              shift; RPKG=$1;;
+	--u|--libunwind)     shift; UVER=$1;;
+	--uenv)              shift; UENV=$1;;
+	-ou|--ov-libuinwind) shift; UOVL=$1;;
+	--ucat)              shift; UCAT=$1;;
+	--upkg)              shift; UPKG=$1;;
+	--a|--libcxxabi)     shift; AVER=$1;;
+	--aenv)              shift; AENV=$1;;
+	-oa|--ov--libcxxabi) shift; AOVL=$1;;
+	--acat)              shift; ACAT=$1;;
+	--apkg)              shift; APKG=$1;;
+	--p|--libcxx)        shift; PVER=$1;;
+	--penv)              shift; PENV=$1;;
+	-op|--ov-libcxx)     shift; POVL=$1;;
+	--pcat)              shift; PCAT=$1;;
+	--ppkg)              shift; PPKG=$1;;
+	--c|--ccw)           shift; CVER=$1;;
+	--cenv)              shift; CENV=$1;;
+	-oc|--ov-ccw)        shift; COVL=$1;;
+	--ccat)              shift; CCAT=$1;;
+	--cpkg)              shift; CPKG=$1;;
+	-ox|--ov-extra)      shift; XOVLS+=( "$1" );;
+	--env)               shift; AENV=$1;;
+	-L|--llvm)           LLVM="yes";;
+	-A|--abis)           shift; MULTILIB_ABIS=$1;;
+	--host-abi)          shift; HOST_ABI=$1;;
+	-S|--stable)         DEFAULT_VER="[stable]";;
+	-C|--clean)          shift; parse_target $1; ACTION="uninstall";;
+	-s?|--stage?)        STAGE=${1:0-1};;
+	-oS|--overlays)      shift; SEARCH_OVERLAYS=$1;;
+	-oO|--ov-output)     shift; CROSSDEV_OVERLAY=$1;;
+	--ex-only)           EX_FAST="yes";;
+	--ex-gcc)            EX_GCC="yes";;
+	--ex-gdb)            EX_GDB="yes";;
+	--ex-pkg)            shift; XPKGS+=( "$1" );;
+	--with-*)            eval $(set_withval $1);;
+	--without-*)         eval $(set_withval $1);;
+	-f|--force)          FORCE="yes";;
+	-x)                  SET_X="yes";;
+	--show-target-cfg)   SHOW_TARGET_CFG="yes";;
+	--init-target)       INIT_TARGET_ONLY="yes";;
+	--show-fail-log)     SHOW_FAIL_LOG="yes";;
+	--show-repo-cfg)     show_repo_cfg "$2";;
+	-P|--portage)        UOPTS="${UOPTS} $2"; shift;;
+	-h|--help)           usage;;
+	-*)                  eerror "UNKNOWN OPTION: '$1'" ; usage 1;;
+	*)                   parse_target $1;;
 	esac
 	shift
 done
@@ -1038,6 +1056,10 @@ GVER=${GVER:-${DEFAULT_VER}}
 KVER=${KVER:-${DEFAULT_VER}}
 LVER=${LVER:-${DEFAULT_VER}}
 DVER=${DVER:-${DEFAULT_VER}}
+RVER=${RVER:-${DEFAULT_VER}}
+AVER=${AVER:-${DEFAULT_VER}}
+PVER=${PVER:-${DEFAULT_VER}}
+UVER=${UVER:-${DEFAULT_VER}}
 STAGE=${STAGE:-${STAGE_DEFAULT}}
 [[ -z ${CTARGET} ]] && usage 1
 for with in HEADERS ; do
@@ -1054,8 +1076,6 @@ if [[ ${LPKG} == "newlib" && ${LVER} == "[stable]" ]]; then
 	LVER="[latest]"
 fi
 
-RVER="[latest]"
-
 show_target_cfg() {
 	local pkgs crosspkgs=()
 
@@ -1245,6 +1265,12 @@ einfo "headers:               `pretty_atom ${KPKG}- ${KVER}`"
 is_s3 && {
 einfo "libc:                  `pretty_atom ${LPKG}- ${LVER}`"
 }
+is_s4 && {
+[[ "${LLVM}" == "yes" ]] && \
+einfo "llvm-libunwind:        `pretty_atom ${UPKG}- ${UVER}`"
+einfo "libcxxabi:             `pretty_atom ${APKG}- ${AVER}`"
+einfo "libcxx:                `pretty_atom ${PPKG}- ${PVER}`"
+}
 }
 ex_gcc && {
 einfo "Extra: gcc pass:       DO IT"
@@ -1587,7 +1613,7 @@ done
 
 pkglist=( K L )
 if [[ ${LLVM} == "yes" ]] ; then
-	pkglist+=( R C )
+	pkglist+=( R C A P U )
 else
 	pkglist+=( B G D )
 fi
@@ -1770,14 +1796,10 @@ if [[ "${LLVM}" == "yes" ]]; then
 	[[ -d "${CLANG_CROSS_CFG_DIR}" ]] || mkdir -p "${CLANG_CROSS_CFG_DIR}"
 
 	export CLANG_CROSS_CFG="${CLANG_CROSS_CFG_DIR}/${CTARGET}.cfg"
-	# Force --unwindlib=none for now
 	cat <<-EOF > "${CLANG_CROSS_CFG}"
-	--rtlib=compiler-rt
 	--sysroot=/usr/${CTARGET}
 	--target=${CTARGET}
-	--unwindlib=libunwind
-	--stdlib=libc++
-	-fuse-ld=lld
+	@../gentoo-runtimes.cfg
 	EOF
 	# Workaround until LLVM libc supports dynamic linking and SSP
 	[[ "${LPKG}" == "llvm-libc" ]] && cat <<-EOF >> "${CLANG_CROSS_CFG}"
@@ -1885,10 +1907,22 @@ if ! ex_fast ; then
 	fi
 
 	# stage4: full compiler (C/C++/etc...)
-	if is_s4 && [[ "${LLVM}" != "yes" ]] ; then
-		EOPTS="${EOPTS_UP} --newuse" \
-		USE="${GUSE} ${USE} ${GUSE_DISABLE_STAGE_2}" \
-			doemerge ${GPKG} ${GPKG}-stage2
+	if is_s4 ; then
+		if [[ "${LLVM}" == "yes" ]]; then
+			# Static llvm-libunwind is essential for supporting simple static linking in
+			# general, see the bug #892956. The same is done in the LLVM profile.
+			USE="${UUSE} ${USE} static-libs" \
+				doemerge ${UPKG}
+
+			USE="${AUSE} ${USE}" \
+				doemerge ${APKG}
+			USE="${PUSE} ${USE}" \
+				doemerge ${PPKG}
+		else
+			EOPTS="${EOPTS_UP} --newuse" \
+			USE="${GUSE} ${USE} ${GUSE_DISABLE_STAGE_2}" \
+				doemerge ${GPKG} ${GPKG}-stage2
+		fi
 	fi
 fi
 
diff --git a/scripts/container_test.sh b/scripts/container_test.sh
index 4205dbd..85311bf 100755
--- a/scripts/container_test.sh
+++ b/scripts/container_test.sh
@@ -6,6 +6,7 @@ print_help() {
 	echo "Usage: $0 [OPTIONS]
 
 Options:
+  --llvm                Use LLVM/Clang as a cross compiler
   --skip-system         Skip emerging the @system set after setting up crossdev.
   --tag <tag>           Specify the container tag to use. Default is 'latest'.
   --target <target>     Specify the target architecture for crossdev. Required.
@@ -54,6 +55,7 @@ CONTAINER_NAME=${CONTAINER_NAME:-"crossdev"}
 CONTAINER_URI=${CONTAINER_URI:-"docker.io/gentoo/stage3"}
 CONTAINER_TAG="latest"
 EMERGE_SYSTEM=1
+USE_LLVM=0
 TOPDIR=$(git rev-parse --show-toplevel)
 
 remove_container || true
@@ -65,6 +67,10 @@ while [[ $# -gt 0 ]]; do
 			print_help
 			exit 0
 			;;
+		--llvm)
+			USE_LLVM=1
+			shift 1
+			;;
 		--skip-system)
 			EMERGE_SYSTEM=0
 			shift 1
@@ -85,7 +91,13 @@ while [[ $# -gt 0 ]]; do
 	esac
 done
 
+EXTRA_ARGS=()
+if [[ "${USE_LLVM}" -eq 1 ]]; then
+	EXTRA_ARGS+="--llvm"
+fi
+
 "${CONTAINER_ENGINE}" run -d \
+	--pull always \
 	--name "${CONTAINER_NAME}" \
 	-v "${TOPDIR}:/workspace" \
 	-w /workspace \
@@ -97,7 +109,7 @@ run_in_container getuto
 run_in_container emerge --getbinpkg app-eselect/eselect-repository sys-apps/config-site
 run_in_container make install
 run_in_container eselect repository create crossdev
-run_in_container crossdev --show-fail-log --target "${TARGET}"
+run_in_container crossdev --show-fail-log "${EXTRA_ARGS[@]}" --target "${TARGET}"
 if [[ "${EMERGE_SYSTEM}" -eq 1 ]]; then
 	run_in_container "${TARGET}-emerge" @system
 fi