Merge updates from master

43 files changed, 3032 insertions, 19 deletions

diff --git a/app-arch/lz4/files/1.10.0-fix-freestanding-test.patch b/app-arch/lz4/files/1.10.0-fix-freestanding-test.patch
new file mode 100644
index 000000000000..f8dfe2a41c64
--- /dev/null
+++ b/app-arch/lz4/files/1.10.0-fix-freestanding-test.patch
@@ -0,0 +1,42 @@
+
+From: https://github.com/lz4/lz4/pull/1468
+
+commit 63267a77d863f63826d8b13ddb8c190d3a4c01c5
+Author: Holger Hoffstätte <holger@applied-asynchrony.com>
+Date:   Mon Jul 22 22:11:19 2024 +0200
+
+    Fix stack alignment of _start() in freestanding test
+    
+    When the freestanding test is built with any kind of optimization
+    that enables vectorized loops, special care must be taken to align
+    the stack for _start() at a 16-byte boundary.
+
+diff --git a/tests/freestanding.c b/tests/freestanding.c
+index 6109aa7..96de9d3 100644
+--- a/tests/freestanding.c
++++ b/tests/freestanding.c
+@@ -225,7 +225,7 @@ EXTERN_C int memcmp(const void *s1, const void *s2, size_t n) {
+ 
+ 
+ //
+-EXTERN_C void _start(void) {
++EXTERN_C void __attribute__((force_align_arg_pointer)) _start(void) {
+     test();
+     MY_exit(0);
+ }
+
+Disable the stack protector to allow building with clang.
+See https://bugs.gentoo.org/936480
+
+diff -up lz4-1.10.0/build/meson/meson/tests/meson.build lz4-1.10.0/build/meson/meson/tests/meson.build
+--- lz4-1.10.0/build/meson/meson/tests/meson.build	2024-07-21 19:29:49.000000000 +0200
++++ lz4-1.10.0/build/meson/meson/tests/meson.build	2024-07-23 01:26:40.561113031 +0200
+@@ -47,7 +47,7 @@ test_exes = {
+   },
+   'freestanding': {
+     'sources': files(lz4_source_root / 'tests/freestanding.c'),
+-    'c_args': ['-ffreestanding', '-Wno-unused-parameter', '-Wno-declaration-after-statement'],
++    'c_args': ['-ffreestanding', '-fno-stack-protector', '-Wno-unused-parameter', '-Wno-declaration-after-statement'],
+     'link_args': ['-nostdlib'],
+     'build': cc.get_id() in ['gcc', 'clang'] and
+       host_machine.system() == 'linux' and host_machine.cpu_family() == 'x86_64',
diff --git a/app-arch/lz4/lz4-1.10.0-r1.ebuild b/app-arch/lz4/lz4-1.10.0-r1.ebuild
index d05fa3dd02fb..7cbc02aadc78 100644
--- a/app-arch/lz4/lz4-1.10.0-r1.ebuild
+++ b/app-arch/lz4/lz4-1.10.0-r1.ebuild
@@ -17,6 +17,10 @@ RESTRICT="!test? ( test )"
 
 EMESON_SOURCE=${S}/build/meson
 
+PATCHES=(
+	"${FILESDIR}/${PV}-fix-freestanding-test.patch"
+)
+
 multilib_src_configure() {
 	local emesonargs=(
 		-Dtests=$(usex test true false)
diff --git a/dev-debug/lldb/lldb-20.0.0.9999.ebuild b/dev-debug/lldb/lldb-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..c79bdcdf6f3d
--- /dev/null
+++ b/dev-debug/lldb/lldb-20.0.0.9999.ebuild
@@ -0,0 +1,110 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..12} )
+inherit cmake flag-o-matic llvm.org llvm-utils python-single-r1
+
+DESCRIPTION="The LLVM debugger"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0/${LLVM_SOABI}"
+IUSE="+debug debuginfod +libedit lzma ncurses +python test +xml"
+RESTRICT="test"
+REQUIRED_USE=${PYTHON_REQUIRED_USE}
+
+DEPEND="
+	debuginfod? (
+		net-misc/curl:=
+		dev-cpp/cpp-httplib:=
+	)
+	libedit? ( dev-libs/libedit:0= )
+	lzma? ( app-arch/xz-utils:= )
+	ncurses? ( >=sys-libs/ncurses-5.9-r3:0= )
+	xml? ( dev-libs/libxml2:= )
+	~sys-devel/clang-${PV}
+	~sys-devel/llvm-${PV}[debuginfod=]
+"
+RDEPEND="
+	${DEPEND}
+	python? (
+		${PYTHON_DEPS}
+	)
+"
+BDEPEND="
+	${PYTHON_DEPS}
+	python? (
+		>=dev-lang/swig-3.0.11
+	)
+	test? (
+		$(python_gen_cond_dep "
+			~dev-python/lit-${PV}[\${PYTHON_USEDEP}]
+			dev-python/psutil[\${PYTHON_USEDEP}]
+		")
+		sys-devel/lld
+	)
+"
+
+LLVM_COMPONENTS=( lldb cmake llvm/utils )
+LLVM_TEST_COMPONENTS=( llvm/lib/Testing/Support third-party )
+llvm.org_set_globals
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# bug #858389 (https://github.com/llvm/llvm-project/issues/83636)
+	filter-lto
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+
+	local mycmakeargs=(
+		-DLLDB_ENABLE_CURSES=$(usex ncurses)
+		-DLLDB_ENABLE_LIBEDIT=$(usex libedit)
+		-DLLDB_ENABLE_PYTHON=$(usex python)
+		-DLLDB_ENABLE_LUA=OFF
+		-DLLDB_ENABLE_LZMA=$(usex lzma)
+		-DLLDB_ENABLE_LIBXML2=$(usex xml)
+		-DLLVM_ENABLE_TERMINFO=$(usex ncurses)
+
+		-DLLDB_INCLUDE_TESTS=$(usex test)
+
+		-DCLANG_LINK_CLANG_DYLIB=ON
+		# TODO: fix upstream to detect this properly
+		-DHAVE_LIBDL=ON
+		-DHAVE_LIBPTHREAD=ON
+
+		# normally we'd have to set LLVM_ENABLE_TERMINFO, HAVE_TERMINFO
+		# and TERMINFO_LIBS... so just force FindCurses.cmake to use
+		# ncurses with complete library set (including autodetection
+		# of -ltinfo)
+		-DCURSES_NEED_NCURSES=ON
+
+		-DCLANG_RESOURCE_DIR="../../../clang/${LLVM_MAJOR}"
+
+		-DLLVM_MAIN_SRC_DIR="${WORKDIR}/llvm"
+		-DPython3_EXECUTABLE="${PYTHON}"
+	)
+	use test && mycmakeargs+=(
+		-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	cmake_src_configure
+}
+
+src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-lldb-{shell,unit}
+	# failures + hangs
+	#use python && cmake_build check-lldb-api
+}
+
+src_install() {
+	cmake_src_install
+	find "${D}" -name '*.a' -delete || die
+
+	use python && python_optimize
+}
diff --git a/dev-libs/libclc/libclc-20.0.0.9999.ebuild b/dev-libs/libclc/libclc-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..2b8c5e63c257
--- /dev/null
+++ b/dev-libs/libclc/libclc-20.0.0.9999.ebuild
@@ -0,0 +1,61 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+LLVM_COMPAT=( {17..18} )
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake llvm.org llvm-r1 python-any-r1
+
+DESCRIPTION="OpenCL C library"
+HOMEPAGE="https://libclc.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( MIT BSD )"
+SLOT="0"
+IUSE="+spirv video_cards_nvidia video_cards_r600 video_cards_radeonsi"
+
+BDEPEND="
+	${PYTHON_DEPS}
+	$(llvm_gen_dep '
+		sys-devel/clang:${LLVM_SLOT}
+		spirv? ( dev-util/spirv-llvm-translator:${LLVM_SLOT} )
+	')
+"
+
+LLVM_COMPONENTS=( libclc )
+llvm.org_set_globals
+
+pkg_setup() {
+	llvm-r1_pkg_setup
+	python-any-r1_pkg_setup
+}
+
+src_configure() {
+	local libclc_targets=()
+
+	use spirv && libclc_targets+=(
+		"spirv-mesa3d-"
+		"spirv64-mesa3d-"
+	)
+	use video_cards_nvidia && libclc_targets+=(
+		"nvptx--"
+		"nvptx64--"
+		"nvptx--nvidiacl"
+		"nvptx64--nvidiacl"
+	)
+	use video_cards_r600 && libclc_targets+=(
+		"r600--"
+	)
+	use video_cards_radeonsi && libclc_targets+=(
+		"amdgcn--"
+		"amdgcn-mesa-mesa3d"
+		"amdgcn--amdhsa"
+	)
+	[[ ${#libclc_targets[@]} ]] || die "libclc target missing!"
+
+	libclc_targets=${libclc_targets[*]}
+	local mycmakeargs=(
+		-DLIBCLC_TARGETS_TO_BUILD="${libclc_targets// /;}"
+	)
+	cmake_src_configure
+}
diff --git a/dev-ml/llvm-ocaml/llvm-ocaml-20.0.0.9999.ebuild b/dev-ml/llvm-ocaml/llvm-ocaml-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..36b3716c0372
--- /dev/null
+++ b/dev-ml/llvm-ocaml/llvm-ocaml-20.0.0.9999.ebuild
@@ -0,0 +1,107 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake llvm.org llvm-utils python-any-r1
+
+DESCRIPTION="OCaml bindings for LLVM"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0/${PV}"
+IUSE="+debug test"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	>=dev-lang/ocaml-4.00.0:0=
+	dev-ml/ocaml-ctypes:=
+	~sys-devel/llvm-${PV}:=[debug?]
+	!sys-devel/llvm[ocaml(-)]
+"
+
+DEPEND="
+	${RDEPEND}
+"
+BDEPEND="
+	${PYTHON_DEPS}
+	dev-lang/perl
+	dev-ml/findlib
+"
+
+LLVM_COMPONENTS=( llvm cmake third-party )
+LLVM_USE_TARGETS=llvm
+llvm.org_set_globals
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DBUILD_SHARED_LIBS=OFF
+		-DLLVM_BUILD_LLVM_DYLIB=ON
+		-DLLVM_LINK_LLVM_DYLIB=ON
+		-DLLVM_OCAML_OUT_OF_TREE=ON
+
+		# cheap hack: LLVM combines both anyway, and the only difference
+		# is that the former list is explicitly verified at cmake time
+		-DLLVM_TARGETS_TO_BUILD=""
+		-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD="${LLVM_TARGETS// /;}"
+		-DLLVM_BUILD_TESTS=$(usex test)
+
+		# disable various irrelevant deps and settings
+		-DLLVM_ENABLE_FFI=OFF
+		-DLLVM_ENABLE_TERMINFO=OFF
+		-DHAVE_HISTEDIT_H=NO
+		-DLLVM_ENABLE_ASSERTIONS=$(usex debug)
+		-DLLVM_ENABLE_EH=ON
+		-DLLVM_ENABLE_RTTI=ON
+
+		-DLLVM_HOST_TRIPLE="${CHOST}"
+
+		-DPython3_EXECUTABLE="${PYTHON}"
+
+		# TODO: ocamldoc
+	)
+
+	use test && mycmakeargs+=(
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	# also: custom rules for OCaml do not work for CPPFLAGS
+	use debug || local -x CFLAGS="${CFLAGS} -DNDEBUG"
+	cmake_src_configure
+
+	local llvm_libdir=$(llvm-config --libdir)
+	# an ugly hack; TODO: figure out a way to pass -L to ocaml...
+	cd "${BUILD_DIR}/${libdir}" || die
+	ln -s "${llvm_libdir}"/*.so . || die
+
+	if use test; then
+		local llvm_bindir=$(llvm-config --bindir)
+		# Force using system-installed tools.
+		sed -i -e "/llvm_tools_dir/s@\".*\"@\"${llvm_bindir}\"@" \
+			"${BUILD_DIR}"/test/lit.site.cfg.py || die
+	fi
+}
+
+src_compile() {
+	cmake_build ocaml_all
+}
+
+src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-llvm-bindings-ocaml
+}
+
+src_install() {
+	DESTDIR="${D}" \
+	cmake -P "${BUILD_DIR}"/bindings/ocaml/cmake_install.cmake || die
+
+	dodoc bindings/ocaml/README.txt
+}
diff --git a/dev-python/clang-python/clang-python-20.0.0.9999.ebuild b/dev-python/clang-python/clang-python-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..7f3de6814bbb
--- /dev/null
+++ b/dev-python/clang-python/clang-python-20.0.0.9999.ebuild
@@ -0,0 +1,53 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit llvm.org python-r1
+
+DESCRIPTION="Python bindings for sys-devel/clang"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0"
+IUSE="test"
+RESTRICT="!test? ( test )"
+REQUIRED_USE="${PYTHON_REQUIRED_USE}"
+
+# The module is opening libclang.so directly, and doing some blasphemy
+# on top of it.
+DEPEND="
+	>=sys-devel/clang-${PV}:*
+	!sys-devel/llvm:0[clang(-),python(-)]
+	!sys-devel/clang:0[python(-)]
+"
+RDEPEND="
+	${DEPEND}
+	${PYTHON_DEPS}
+"
+BDEPEND="
+	${PYTHON_DEPS}
+	test? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+"
+
+LLVM_COMPONENTS=( clang/bindings/python )
+llvm.org_set_globals
+
+python_test() {
+	# tests rely on results from a specific clang version, so override
+	# the search path
+	local -x CLANG_LIBRARY_PATH=${BROOT}/usr/lib/llvm/${LLVM_MAJOR}/$(get_libdir)
+	local -x CLANG_NO_DEFAULT_CONFIG=1
+	"${EPYTHON}" -m unittest discover -v || die "Tests fail with ${EPYTHON}"
+}
+
+src_test() {
+	python_foreach_impl python_test
+}
+
+src_install() {
+	python_foreach_impl python_domodule clang
+}
diff --git a/dev-python/lit/lit-18.1.8.ebuild b/dev-python/lit/lit-18.1.8.ebuild
index acdd5d2d1660..6b9e078a9f68 100644
--- a/dev-python/lit/lit-18.1.8.ebuild
+++ b/dev-python/lit/lit-18.1.8.ebuild
@@ -13,7 +13,7 @@ HOMEPAGE="https://llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
 SLOT="0"
-KEYWORDS="amd64 arm arm64 ~loong ~mips ppc ppc64 ~riscv ~sparc x86"
+KEYWORDS="amd64 arm arm64 ~loong ~mips ppc ppc64 ~riscv sparc x86"
 IUSE="test"
 RESTRICT="!test? ( test )"
 
diff --git a/dev-python/lit/lit-20.0.0.9999.ebuild b/dev-python/lit/lit-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..d862b4f8cd03
--- /dev/null
+++ b/dev-python/lit/lit-20.0.0.9999.ebuild
@@ -0,0 +1,45 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+DISTUTILS_USE_PEP517=setuptools
+PYTHON_COMPAT=( python3_{10..13} )
+
+inherit distutils-r1 llvm.org
+
+DESCRIPTION="A stand-alone install of the LLVM suite testing tool"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0"
+IUSE="test"
+RESTRICT="!test? ( test )"
+
+# Tests require 'FileCheck' and 'not' utilities (from llvm)
+BDEPEND="
+	test? (
+		dev-python/psutil[${PYTHON_USEDEP}]
+		sys-devel/llvm
+	)
+"
+
+LLVM_COMPONENTS=( llvm/utils/lit )
+llvm.org_set_globals
+
+# TODO: move the manpage generation here (from sys-devel/llvm)
+
+src_prepare() {
+	# flaky test
+	# https://github.com/llvm/llvm-project/issues/72022
+	rm tests/progress-bar.py || die
+
+	cd "${WORKDIR}" || die
+	distutils-r1_src_prepare
+}
+
+python_test() {
+	local -x LIT_PRESERVES_TMP=1
+	local litflags=$(get_lit_flags)
+	./lit.py ${litflags//;/ } tests || die
+}
diff --git a/eclass/llvm-r1.eclass b/eclass/llvm-r1.eclass
index 075df9218be8..0a53b9a3cb5e 100644
--- a/eclass/llvm-r1.eclass
+++ b/eclass/llvm-r1.eclass
@@ -61,7 +61,7 @@ _LLVM_OLDEST_SLOT=15
 # @DESCRIPTION:
 # The newest stable LLVM version.  Versions newer than that won't
 # be automatically enabled via USE defaults.
-_LLVM_NEWEST_STABLE=17
+_LLVM_NEWEST_STABLE=18
 
 # == control variables ==
 
@@ -123,11 +123,16 @@ _llvm_set_globals() {
 	fi
 
 	if [[ ${stable[@]} ]]; then
+		# If there is at least one stable slot supported, then enable
+		# the newest stable slot by default.
 		IUSE="+llvm_slot_${stable[-1]}"
 		unset 'stable[-1]'
 	else
-		IUSE="+llvm_slot_${unstable[-1]}"
-		unset 'unstable[-1]'
+		# Otherwise, enable the "oldest" ~arch slot.  We really only
+		# expect a single ~arch version, so this primarily prevents
+		# defaulting to non-keyworded slots.
+		IUSE="+llvm_slot_${unstable[0]}"
+		unset 'unstable[0]'
 	fi
 	local nondefault=( "${stable[@]}" "${unstable[@]}" )
 	IUSE+=" ${nondefault[*]/#/llvm_slot_}"
diff --git a/eclass/llvm.eclass b/eclass/llvm.eclass
index e297fe992c9f..bb5ff5d78290 100644
--- a/eclass/llvm.eclass
+++ b/eclass/llvm.eclass
@@ -9,6 +9,7 @@
 # @SUPPORTED_EAPIS: 7 8
 # @PROVIDES: llvm-utils
 # @BLURB: Utility functions to build against slotted LLVM
+# @DEPRECATED: llvm-r1.eclass
 # @DESCRIPTION:
 # The llvm.eclass provides utility functions that can be used to build
 # against specific version of slotted LLVM (with fallback to :0 for old
diff --git a/eclass/llvm.org.eclass b/eclass/llvm.org.eclass
index 7aa1d0e2b0b8..d2797f46bb92 100644
--- a/eclass/llvm.org.eclass
+++ b/eclass/llvm.org.eclass
@@ -57,7 +57,7 @@ LLVM_VERSION=$(ver_cut 1-3)
 # @DESCRIPTION:
 # The major version of current LLVM trunk.  Used to determine
 # the correct branch to use.
-_LLVM_MAIN_MAJOR=19
+_LLVM_MAIN_MAJOR=20
 
 # @ECLASS_VARIABLE: _LLVM_SOURCE_TYPE
 # @INTERNAL
diff --git a/net-wireless/blueman/blueman-2.4.2.ebuild b/net-wireless/blueman/blueman-2.4.2.ebuild
index d593d644bf14..806f7a6d29d5 100644
--- a/net-wireless/blueman/blueman-2.4.2.ebuild
+++ b/net-wireless/blueman/blueman-2.4.2.ebuild
@@ -41,6 +41,7 @@ BDEPEND="
 		dev-python/cython[${PYTHON_USEDEP}]
 		test? (
 			dev-python/python-dbusmock[${PYTHON_USEDEP}]
+			media-libs/libpulse
 			>=net-misc/networkmanager-0.8[introspection]
 		)
 	')
diff --git a/net-wireless/blueman/blueman-9999.ebuild b/net-wireless/blueman/blueman-9999.ebuild
index eb7eface474e..697c7faeab72 100644
--- a/net-wireless/blueman/blueman-9999.ebuild
+++ b/net-wireless/blueman/blueman-9999.ebuild
@@ -41,6 +41,7 @@ BDEPEND="
 		dev-python/cython[${PYTHON_USEDEP}]
 		test? (
 			dev-python/python-dbusmock[${PYTHON_USEDEP}]
+			media-libs/libpulse
 			>=net-misc/networkmanager-0.8[introspection]
 		)
 	')
diff --git a/sys-devel/clang-common/clang-common-17.0.6-r6.ebuild b/sys-devel/clang-common/clang-common-17.0.6-r6.ebuild
index f90ed723d7b0..bcf06a6f7f17 100644
--- a/sys-devel/clang-common/clang-common-17.0.6-r6.ebuild
+++ b/sys-devel/clang-common/clang-common-17.0.6-r6.ebuild
@@ -10,7 +10,7 @@ HOMEPAGE="https://llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
 SLOT="0"
-KEYWORDS="~amd64 ~arm ~arm64 ~loong ~ppc ~ppc64 ~riscv ~sparc ~x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
+KEYWORDS="~amd64 ~arm ~arm64 ~loong ppc ~ppc64 ~riscv ~sparc ~x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
 IUSE="
 	default-compiler-rt default-libcxx default-lld
 	bootstrap-prefix cet hardened llvm-libunwind
diff --git a/sys-devel/clang-common/clang-common-18.1.8-r1.ebuild b/sys-devel/clang-common/clang-common-18.1.8-r1.ebuild
index db5d2595dac9..ceeb2fd3046f 100644
--- a/sys-devel/clang-common/clang-common-18.1.8-r1.ebuild
+++ b/sys-devel/clang-common/clang-common-18.1.8-r1.ebuild
@@ -10,7 +10,7 @@ HOMEPAGE="https://llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
 SLOT="0"
-KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv ~sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
 IUSE="
 	default-compiler-rt default-libcxx default-lld
 	bootstrap-prefix cet hardened llvm-libunwind
diff --git a/sys-devel/clang-common/clang-common-20.0.0.9999.ebuild b/sys-devel/clang-common/clang-common-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..090a45690818
--- /dev/null
+++ b/sys-devel/clang-common/clang-common-20.0.0.9999.ebuild
@@ -0,0 +1,304 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit bash-completion-r1 llvm.org multilib
+
+DESCRIPTION="Common files shared between multiple slots of clang"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0"
+IUSE="
+	default-compiler-rt default-libcxx default-lld
+	bootstrap-prefix cet hardened llvm-libunwind
+"
+
+PDEPEND="
+	sys-devel/clang:*
+	default-compiler-rt? (
+		sys-devel/clang-runtime[compiler-rt]
+		llvm-libunwind? ( sys-libs/llvm-libunwind[static-libs] )
+		!llvm-libunwind? ( sys-libs/libunwind[static-libs] )
+	)
+	!default-compiler-rt? ( sys-devel/gcc )
+	default-libcxx? ( >=sys-libs/libcxx-${PV}[static-libs] )
+	!default-libcxx? ( sys-devel/gcc )
+	default-lld? ( >=sys-devel/lld-${PV} )
+	!default-lld? ( sys-devel/binutils )
+"
+IDEPEND="
+	!default-compiler-rt? ( sys-devel/gcc-config )
+	!default-libcxx? ( sys-devel/gcc-config )
+"
+
+LLVM_COMPONENTS=( clang/utils )
+llvm.org_set_globals
+
+pkg_pretend() {
+	[[ ${CLANG_IGNORE_DEFAULT_RUNTIMES} ]] && return
+
+	local flag missing_flags=()
+	for flag in default-{compiler-rt,libcxx,lld}; do
+		if ! use "${flag}" && has_version "sys-devel/clang[${flag}]"; then
+			missing_flags+=( "${flag}" )
+		fi
+	done
+
+	if [[ ${missing_flags[@]} ]]; then
+		eerror "It seems that you have the following flags set on sys-devel/clang:"
+		eerror
+		eerror "  ${missing_flags[*]}"
+		eerror
+		eerror "The default runtimes are now set via flags on sys-devel/clang-common."
+		eerror "The build is being aborted to prevent breakage.  Please either set"
+		eerror "the respective flags on this ebuild, e.g.:"
+		eerror
+		eerror "  sys-devel/clang-common ${missing_flags[*]}"
+		eerror
+		eerror "or build with CLANG_IGNORE_DEFAULT_RUNTIMES=1."
+		die "Mismatched defaults detected between sys-devel/clang and sys-devel/clang-common"
+	fi
+}
+
+_doclang_cfg() {
+	local triple="${1}"
+
+	local tool
+	for tool in ${triple}-clang{,++}; do
+		newins - "${tool}.cfg" <<-EOF
+			# This configuration file is used by ${tool} driver.
+			@gentoo-common.cfg
+			@gentoo-common-ld.cfg
+		EOF
+		if [[ ${triple} == x86_64* ]]; then
+			cat >> "${ED}/etc/clang/${tool}.cfg" <<-EOF || die
+				@gentoo-cet.cfg
+			EOF
+		fi
+	done
+
+	if use kernel_Darwin; then
+		cat >> "${ED}/etc/clang/${triple}-clang++.cfg" <<-EOF || die
+			-lc++abi
+		EOF
+	fi
+
+	newins - "${triple}-clang-cpp.cfg" <<-EOF
+		# This configuration file is used by the ${triple}-clang-cpp driver.
+		@gentoo-common.cfg
+	EOF
+	if [[ ${triple} == x86_64* ]]; then
+		cat >> "${ED}/etc/clang/${triple}-clang-cpp.cfg" <<-EOF || die
+			@gentoo-cet.cfg
+		EOF
+	fi
+
+	# Install symlinks for triples with other vendor strings since some
+	# programs insist on mangling the triple.
+	local vendor
+	for vendor in gentoo pc unknown; do
+		local vendor_triple="${triple%%-*}-${vendor}-${triple#*-*-}"
+		for tool in clang{,++,-cpp}; do
+			if [[ ! -f "${ED}/etc/clang/${vendor_triple}-${tool}.cfg" ]]; then
+				dosym "${triple}-${tool}.cfg" "/etc/clang/${vendor_triple}-${tool}.cfg"
+			fi
+		done
+	done
+}
+
+doclang_cfg() {
+	local triple="${1}"
+
+	_doclang_cfg ${triple}
+
+	# LLVM may have different arch names in some cases. For example in x86
+	# profiles the triple uses i686, but llvm will prefer i386 if invoked
+	# with "clang" on x86 or "clang -m32" on x86_64. The gentoo triple will
+	# be used if invoked through ${CHOST}-clang{,++,-cpp} though.
+	#
+	# To make sure the correct triples are installed,
+	# see Triple::getArchTypeName() in llvm/lib/TargetParser/Triple.cpp
+	# and compare with CHOST values in profiles.
+
+	local abi=${triple%%-*}
+	case ${abi} in
+		armv4l|armv4t|armv5tel|armv6j|armv7a)
+			_doclang_cfg ${triple/${abi}/arm}
+			;;
+		i686)
+			_doclang_cfg ${triple/${abi}/i386}
+			;;
+		sparc)
+			_doclang_cfg ${triple/${abi}/sparcel}
+			;;
+		sparc64)
+			_doclang_cfg ${triple/${abi}/sparcv9}
+			;;
+	esac
+}
+
+src_install() {
+	newbashcomp bash-autocomplete.sh clang
+
+	insinto /etc/clang
+	newins - gentoo-runtimes.cfg <<-EOF
+		# This file is initially generated by sys-devel/clang-runtime.
+		# It is used to control the default runtimes using by clang.
+
+		--rtlib=$(usex default-compiler-rt compiler-rt libgcc)
+		--unwindlib=$(usex default-compiler-rt libunwind libgcc)
+		--stdlib=$(usex default-libcxx libc++ libstdc++)
+		-fuse-ld=$(usex default-lld lld bfd)
+	EOF
+
+	newins - gentoo-gcc-install.cfg <<-EOF
+		# This file is maintained by gcc-config.
+		# It is used to specify the selected GCC installation.
+	EOF
+
+	newins - gentoo-common.cfg <<-EOF
+		# This file contains flags common to clang, clang++ and clang-cpp.
+		@gentoo-runtimes.cfg
+		@gentoo-gcc-install.cfg
+		@gentoo-hardened.cfg
+		# bug #870001
+		-include "${EPREFIX}/usr/include/gentoo/maybe-stddefs.h"
+	EOF
+
+	# clang-cpp does not like link args being passed to it when directly
+	# invoked, so use a separate configuration file.
+	newins - gentoo-common-ld.cfg <<-EOF
+		# This file contains flags common to clang and clang++
+		@gentoo-hardened-ld.cfg
+	EOF
+
+	# Baseline hardening (bug #851111)
+	newins - gentoo-hardened.cfg <<-EOF
+		# Some of these options are added unconditionally, regardless of
+		# USE=hardened, for parity with sys-devel/gcc.
+		-Xarch_host -fstack-clash-protection
+		-Xarch_host -fstack-protector-strong
+		-fPIE
+		-include "${EPREFIX}/usr/include/gentoo/fortify.h"
+	EOF
+
+	newins - gentoo-cet.cfg <<-EOF
+		-Xarch_host -fcf-protection=$(usex cet full none)
+	EOF
+
+	if use kernel_Darwin; then
+		newins - gentoo-hardened-ld.cfg <<-EOF
+			# There was -Wl,-z,relro here, but it's not supported on Mac
+			# TODO: investigate whether -bind_at_load or -read_only_stubs will do the job
+		EOF
+	else
+		newins - gentoo-hardened-ld.cfg <<-EOF
+			# Some of these options are added unconditionally, regardless of
+			# USE=hardened, for parity with sys-devel/gcc.
+			-Wl,-z,relro
+			-Wl,-z,now
+		EOF
+	fi
+
+	dodir /usr/include/gentoo
+
+	cat >> "${ED}/usr/include/gentoo/maybe-stddefs.h" <<-EOF || die
+	/* __has_include is an extension, but it's fine, because this is only
+	for Clang anyway. */
+	#if defined __has_include && __has_include (<stdc-predef.h>) && !defined(__GLIBC__)
+	# include <stdc-predef.h>
+	#endif
+	EOF
+
+	local fortify_level=$(usex hardened 3 2)
+	# We have to do this because glibc's headers warn if F_S is set
+	# without optimization and that would at the very least be very noisy
+	# during builds and at worst trigger many -Werror builds.
+	cat >> "${ED}/usr/include/gentoo/fortify.h" <<- EOF || die
+	#ifdef __clang__
+	# pragma clang system_header
+	#endif
+	#ifndef _FORTIFY_SOURCE
+	# if defined(__has_feature)
+	#  define __GENTOO_HAS_FEATURE(x) __has_feature(x)
+	# else
+	#  define __GENTOO_HAS_FEATURE(x) 0
+	# endif
+	#
+	# if defined(__STDC_HOSTED__) && __STDC_HOSTED__ == 1
+	#  define __GENTOO_NOT_FREESTANDING 1
+	# else
+	#  define __GENTOO_NOT_FREESTANDING 0
+	# endif
+	#
+	# if defined(__OPTIMIZE__) && __OPTIMIZE__ > 0 && __GENTOO_NOT_FREESTANDING > 0
+	#  if !defined(__SANITIZE_ADDRESS__) && !__GENTOO_HAS_FEATURE(address_sanitizer) && !__GENTOO_HAS_FEATURE(memory_sanitizer)
+	#   define _FORTIFY_SOURCE ${fortify_level}
+	#  endif
+	# endif
+	# undef __GENTOO_HAS_FEATURE
+	# undef __GENTOO_NOT_FREESTANDING
+	#endif
+	EOF
+
+	# TODO: Maybe -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_FAST for
+	# non-hardened?
+	if use hardened ; then
+		cat >> "${ED}/etc/clang/gentoo-hardened.cfg" <<-EOF || die
+			# Options below are conditional on USE=hardened.
+			-Xarch_host -D_GLIBCXX_ASSERTIONS
+
+			# Analogue to GLIBCXX_ASSERTIONS
+			# https://libcxx.llvm.org/UsingLibcxx.html#assertions-mode
+			# https://libcxx.llvm.org/Hardening.html#using-hardened-mode
+			-Xarch_host -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE
+		EOF
+
+		cat >> "${ED}/etc/clang/gentoo-hardened-ld.cfg" <<-EOF || die
+			# Options below are conditional on USE=hardened.
+		EOF
+	fi
+
+	# We only install config files for supported ABIs because unprefixed tools
+	# might be used for crosscompilation where e.g. PIE may not be supported.
+	# See bug #912237 and bug #901247. Just ${CHOST} won't do due to bug #912685.
+	local abi
+	for abi in $(get_all_abis); do
+		local abi_chost=$(get_abi_CHOST "${abi}")
+		doclang_cfg "${abi_chost}"
+	done
+
+	if use kernel_Darwin; then
+		cat >> "${ED}/etc/clang/gentoo-common.cfg" <<-EOF || die
+			# Gentoo Prefix on Darwin
+			-Wl,-search_paths_first
+			-Wl,-rpath,${EPREFIX}/usr/lib
+			-L ${EPREFIX}/usr/lib
+			-isystem ${EPREFIX}/usr/include
+			-isysroot ${EPREFIX}/MacOSX.sdk
+		EOF
+		if use bootstrap-prefix ; then
+			# bootstrap-prefix is only set during stage2 of bootstrapping
+			# Prefix, where EPREFIX is set to EPREFIX/tmp.
+			# Here we need to point it at the future lib dir of the stage3's
+			# EPREFIX.
+			cat >> "${ED}/etc/clang/gentoo-common.cfg" <<-EOF || die
+				-Wl,-rpath,${EPREFIX}/../usr/lib
+			EOF
+		fi
+	fi
+}
+
+pkg_preinst() {
+	if has_version -b sys-devel/gcc-config && has_version sys-devel/gcc
+	then
+		local gcc_path=$(gcc-config --get-lib-path 2>/dev/null)
+		if [[ -n ${gcc_path} ]]; then
+			cat >> "${ED}/etc/clang/gentoo-gcc-install.cfg" <<-EOF
+				--gcc-install-dir="${gcc_path%%:*}"
+			EOF
+		fi
+	fi
+}
diff --git a/sys-devel/clang-runtime/clang-runtime-18.1.8.ebuild b/sys-devel/clang-runtime/clang-runtime-18.1.8.ebuild
index fdc40ff34a92..25889f60d661 100644
--- a/sys-devel/clang-runtime/clang-runtime-18.1.8.ebuild
+++ b/sys-devel/clang-runtime/clang-runtime-18.1.8.ebuild
@@ -10,7 +10,7 @@ HOMEPAGE="https://clang.llvm.org/"
 
 LICENSE="metapackage"
 SLOT="${PV%%.*}"
-KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv ~sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
 IUSE="+compiler-rt libcxx openmp +sanitize"
 REQUIRED_USE="sanitize? ( compiler-rt )"
 
diff --git a/sys-devel/clang-runtime/clang-runtime-20.0.0.9999.ebuild b/sys-devel/clang-runtime/clang-runtime-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..323c0b62c062
--- /dev/null
+++ b/sys-devel/clang-runtime/clang-runtime-20.0.0.9999.ebuild
@@ -0,0 +1,39 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit multilib-build toolchain-funcs
+
+DESCRIPTION="Meta-ebuild for clang runtime libraries"
+HOMEPAGE="https://clang.llvm.org/"
+
+LICENSE="metapackage"
+SLOT="${PV%%.*}"
+IUSE="+compiler-rt libcxx openmp +sanitize"
+REQUIRED_USE="sanitize? ( compiler-rt )"
+
+RDEPEND="
+	compiler-rt? (
+		~sys-libs/compiler-rt-${PV}:${SLOT}[abi_x86_32(+)?,abi_x86_64(+)?]
+		sanitize? (
+			~sys-libs/compiler-rt-sanitizers-${PV}:${SLOT}[abi_x86_32(+)?,abi_x86_64(+)?]
+		)
+	)
+	libcxx? ( >=sys-libs/libcxx-${PV}[${MULTILIB_USEDEP}] )
+	openmp? ( >=sys-libs/libomp-${PV}[${MULTILIB_USEDEP}] )
+"
+
+pkg_pretend() {
+	if tc-is-clang; then
+		ewarn "You seem to be using clang as a system compiler.  As of clang-16,"
+		ewarn "upstream has turned a few warnings that commonly occur during"
+		ewarn "configure script runs into errors by default.  This causes some"
+		ewarn "configure tests to start failing, sometimes resulting in silent"
+		ewarn "breakage, missing functionality or runtime misbehavior.  It is"
+		ewarn "not yet clear whether the change will remain or be reverted."
+		ewarn
+		ewarn "For more information, please see:"
+		ewarn "https://discourse.llvm.org/t/configure-script-breakage-with-the-new-werror-implicit-function-declaration/65213"
+	fi
+}
diff --git a/sys-devel/clang-toolchain-symlinks/clang-toolchain-symlinks-18.ebuild b/sys-devel/clang-toolchain-symlinks/clang-toolchain-symlinks-18.ebuild
index 1260c74400df..436e2673639f 100644
--- a/sys-devel/clang-toolchain-symlinks/clang-toolchain-symlinks-18.ebuild
+++ b/sys-devel/clang-toolchain-symlinks/clang-toolchain-symlinks-18.ebuild
@@ -11,7 +11,7 @@ S=${WORKDIR}
 
 LICENSE="public-domain"
 SLOT="${PV}"
-KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv ~sparc x86 ~amd64-linux ~arm64-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv sparc x86 ~amd64-linux ~arm64-macos ~x64-macos"
 IUSE="gcc-symlinks multilib-symlinks +native-symlinks"
 
 # Blocker for bug #872416
diff --git a/sys-devel/clang-toolchain-symlinks/clang-toolchain-symlinks-20.ebuild b/sys-devel/clang-toolchain-symlinks/clang-toolchain-symlinks-20.ebuild
new file mode 100644
index 000000000000..3496a0f89b67
--- /dev/null
+++ b/sys-devel/clang-toolchain-symlinks/clang-toolchain-symlinks-20.ebuild
@@ -0,0 +1,58 @@
+# Copyright 2022-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit multilib
+
+DESCRIPTION="Symlinks to use Clang on GCC-free system"
+HOMEPAGE="https://wiki.gentoo.org/wiki/Project:LLVM"
+S=${WORKDIR}
+
+LICENSE="public-domain"
+SLOT="${PV}"
+IUSE="gcc-symlinks multilib-symlinks +native-symlinks"
+
+# Blocker for bug #872416
+RDEPEND="
+	!<sys-devel/gcc-config-2.6
+	sys-devel/clang:${SLOT}
+"
+
+src_install() {
+	local tools=()
+
+	if use native-symlinks; then
+		tools+=(
+			cc:clang
+			cpp:clang-cpp
+			c++:clang++
+		)
+	fi
+	if use gcc-symlinks; then
+		tools+=(
+			gcc:clang
+			g++:clang++
+		)
+	fi
+
+	local chosts=( "${CHOST}" )
+	if use multilib-symlinks; then
+		local abi
+		for abi in $(get_all_abis); do
+			chosts+=( "$(get_abi_CHOST "${abi}")" )
+		done
+	fi
+
+	local chost t
+	local dest=/usr/lib/llvm/${SLOT}/bin
+	dodir "${dest}"
+	for t in "${tools[@]}"; do
+		dosym "${t#*:}" "${dest}/${t%:*}"
+	done
+	for chost in "${chosts[@]}"; do
+		for t in "${tools[@]}"; do
+			dosym "${t#*:}" "${dest}/${chost}-${t%:*}"
+		done
+	done
+}
diff --git a/sys-devel/clang/clang-18.1.8.ebuild b/sys-devel/clang/clang-18.1.8.ebuild
index df883e4388ad..25c68d567f93 100644
--- a/sys-devel/clang/clang-18.1.8.ebuild
+++ b/sys-devel/clang/clang-18.1.8.ebuild
@@ -16,7 +16,7 @@ HOMEPAGE="https://llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA MIT"
 SLOT="${LLVM_MAJOR}/${LLVM_SOABI}"
-KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv ~sparc x86 ~amd64-linux ~arm64-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv sparc x86 ~amd64-linux ~arm64-macos ~x64-macos"
 IUSE="debug doc +extra ieee-long-double +pie +static-analyzer test xml"
 REQUIRED_USE="${PYTHON_REQUIRED_USE}"
 RESTRICT="!test? ( test )"
diff --git a/sys-devel/clang/clang-20.0.0.9999.ebuild b/sys-devel/clang/clang-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..87140d676d57
--- /dev/null
+++ b/sys-devel/clang/clang-20.0.0.9999.ebuild
@@ -0,0 +1,469 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+
+inherit cmake llvm.org llvm-utils multilib multilib-minimal
+inherit prefix python-single-r1 toolchain-funcs
+
+DESCRIPTION="C language family frontend for LLVM"
+HOMEPAGE="https://llvm.org/"
+
+# MSVCSetupApi.h: MIT
+# sorttable.js: MIT
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA MIT"
+SLOT="${LLVM_MAJOR}/${LLVM_SOABI}"
+IUSE="+debug doc +extra ieee-long-double +pie +static-analyzer test xml"
+REQUIRED_USE="${PYTHON_REQUIRED_USE}"
+RESTRICT="!test? ( test )"
+
+DEPEND="
+	~sys-devel/llvm-${PV}:${LLVM_MAJOR}=[debug=,${MULTILIB_USEDEP}]
+	static-analyzer? ( dev-lang/perl:* )
+	xml? ( dev-libs/libxml2:2=[${MULTILIB_USEDEP}] )
+"
+
+RDEPEND="
+	${PYTHON_DEPS}
+	${DEPEND}
+	>=sys-devel/clang-common-${PV}
+"
+BDEPEND="
+	${PYTHON_DEPS}
+	test? ( ~sys-devel/lld-${PV} )
+	xml? ( virtual/pkgconfig )
+"
+PDEPEND="
+	~sys-devel/clang-runtime-${PV}
+	sys-devel/clang-toolchain-symlinks:${LLVM_MAJOR}
+"
+
+LLVM_COMPONENTS=(
+	clang clang-tools-extra cmake
+)
+LLVM_MANPAGES=1
+LLVM_TEST_COMPONENTS=(
+	llvm/utils
+)
+LLVM_USE_TARGETS=llvm
+llvm.org_set_globals
+
+[[ -n ${LLVM_MANPAGE_DIST} ]] && BDEPEND+=" doc? ( "
+BDEPEND+="
+	$(python_gen_cond_dep '
+		dev-python/myst-parser[${PYTHON_USEDEP}]
+		dev-python/sphinx[${PYTHON_USEDEP}]
+	')
+"
+[[ -n ${LLVM_MANPAGE_DIST} ]] && BDEPEND+=" ) "
+
+# Multilib notes:
+# 1. ABI_* flags control ABIs libclang* is built for only.
+# 2. clang is always capable of compiling code for all ABIs for enabled
+#    target. However, you will need appropriate crt* files (installed
+#    e.g. by sys-devel/gcc and sys-libs/glibc).
+# 3. ${CHOST}-clang wrappers are always installed for all ABIs included
+#    in the current profile (i.e. alike supported by sys-devel/gcc).
+#
+# Therefore: use sys-devel/clang[${MULTILIB_USEDEP}] only if you need
+# multilib clang* libraries (not runtime, not wrappers).
+
+src_prepare() {
+	# create extra parent dir for relative CLANG_RESOURCE_DIR access
+	mkdir -p x/y || die
+	BUILD_DIR=${WORKDIR}/x/y/clang
+
+	llvm.org_src_prepare
+
+	# add Gentoo Portage Prefix for Darwin (see prefix-dirs.patch)
+	eprefixify \
+		lib/Lex/InitHeaderSearch.cpp \
+		lib/Driver/ToolChains/Darwin.cpp || die
+
+	if ! use prefix-guest && [[ -n ${EPREFIX} ]]; then
+		sed -i "/LibDir.*Loader/s@return \"\/\"@return \"${EPREFIX}/\"@" lib/Driver/ToolChains/Linux.cpp || die
+	fi
+}
+
+check_distribution_components() {
+	if [[ ${CMAKE_MAKEFILE_GENERATOR} == ninja ]]; then
+		local all_targets=() my_targets=() l
+		cd "${BUILD_DIR}" || die
+
+		while read -r l; do
+			if [[ ${l} == install-*-stripped:* ]]; then
+				l=${l#install-}
+				l=${l%%-stripped*}
+
+				case ${l} in
+					# meta-targets
+					clang-libraries|distribution)
+						continue
+						;;
+					# tools
+					clang|clangd|clang-*)
+						;;
+					# static libraries
+					clang*|findAllSymbols)
+						continue
+						;;
+					# conditional to USE=doc
+					docs-clang-html|docs-clang-tools-html)
+						use doc || continue
+						;;
+				esac
+
+				all_targets+=( "${l}" )
+			fi
+		done < <(${NINJA} -t targets all)
+
+		while read -r l; do
+			my_targets+=( "${l}" )
+		done < <(get_distribution_components $"\n")
+
+		local add=() remove=()
+		for l in "${all_targets[@]}"; do
+			if ! has "${l}" "${my_targets[@]}"; then
+				add+=( "${l}" )
+			fi
+		done
+		for l in "${my_targets[@]}"; do
+			if ! has "${l}" "${all_targets[@]}"; then
+				remove+=( "${l}" )
+			fi
+		done
+
+		if [[ ${#add[@]} -gt 0 || ${#remove[@]} -gt 0 ]]; then
+			eqawarn "get_distribution_components() is outdated!"
+			eqawarn "   Add: ${add[*]}"
+			eqawarn "Remove: ${remove[*]}"
+		fi
+		cd - >/dev/null || die
+	fi
+}
+
+get_distribution_components() {
+	local sep=${1-;}
+
+	local out=(
+		# common stuff
+		clang-cmake-exports
+		clang-headers
+		clang-resource-headers
+		libclang-headers
+
+		aarch64-resource-headers
+		arm-common-resource-headers
+		arm-resource-headers
+		core-resource-headers
+		cuda-resource-headers
+		hexagon-resource-headers
+		hip-resource-headers
+		hlsl-resource-headers
+		mips-resource-headers
+		opencl-resource-headers
+		openmp-resource-headers
+		ppc-htm-resource-headers
+		ppc-resource-headers
+		riscv-resource-headers
+		systemz-resource-headers
+		utility-resource-headers
+		ve-resource-headers
+		webassembly-resource-headers
+		windows-resource-headers
+		x86-resource-headers
+
+		# libs
+		clang-cpp
+		libclang
+	)
+
+	if multilib_is_native_abi; then
+		out+=(
+			# common stuff
+			bash-autocomplete
+			libclang-python-bindings
+
+			# tools
+			amdgpu-arch
+			c-index-test
+			clang
+			clang-format
+			clang-installapi
+			clang-linker-wrapper
+			clang-offload-bundler
+			clang-offload-packager
+			clang-refactor
+			clang-repl
+			clang-rename
+			clang-scan-deps
+			diagtool
+			hmaptool
+			nvptx-arch
+
+			# needed for cross-compiling Clang
+			clang-tblgen
+		)
+
+		if use extra; then
+			out+=(
+				# extra tools
+				clang-apply-replacements
+				clang-change-namespace
+				clang-doc
+				clang-include-cleaner
+				clang-include-fixer
+				clang-move
+				clang-pseudo
+				clang-query
+				clang-reorder-fields
+				clang-tidy
+				clang-tidy-headers
+				clangd
+				find-all-symbols
+				modularize
+				pp-trace
+			)
+		fi
+
+		if llvm_are_manpages_built; then
+			out+=( docs-clang-man )
+			use extra && out+=( docs-clang-tools-man )
+		fi
+
+		if use doc; then
+			out+=( docs-clang-html )
+			use extra && out+=( docs-clang-tools-html )
+		fi
+
+		use static-analyzer && out+=(
+			clang-check
+			clang-extdef-mapping
+			scan-build
+			scan-build-py
+			scan-view
+		)
+	fi
+
+	printf "%s${sep}" "${out[@]}"
+}
+
+multilib_src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	local mycmakeargs=(
+		-DDEFAULT_SYSROOT=$(usex prefix-guest "" "${EPREFIX}")
+		-DCMAKE_INSTALL_PREFIX="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}"
+		-DCMAKE_INSTALL_MANDIR="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+		-DCLANG_CONFIG_FILE_SYSTEM_DIR="${EPREFIX}/etc/clang"
+		# relative to bindir
+		-DCLANG_RESOURCE_DIR="../../../../lib/clang/${LLVM_MAJOR}"
+
+		-DBUILD_SHARED_LIBS=OFF
+		-DCLANG_LINK_CLANG_DYLIB=ON
+		-DLLVM_DISTRIBUTION_COMPONENTS=$(get_distribution_components)
+		-DCLANG_INCLUDE_TESTS=$(usex test)
+
+		-DLLVM_TARGETS_TO_BUILD="${LLVM_TARGETS// /;}"
+
+		# these are not propagated reliably, so redefine them
+		-DLLVM_ENABLE_EH=ON
+		-DLLVM_ENABLE_RTTI=ON
+
+		# libgomp support fails to find headers without explicit -I
+		# furthermore, it provides only syntax checking
+		-DCLANG_DEFAULT_OPENMP_RUNTIME=libomp
+
+		-DCLANG_DEFAULT_PIE_ON_LINUX=$(usex pie)
+
+		-DCLANG_ENABLE_LIBXML2=$(usex xml)
+		-DCLANG_ENABLE_ARCMT=$(usex static-analyzer)
+		-DCLANG_ENABLE_STATIC_ANALYZER=$(usex static-analyzer)
+		# TODO: CLANG_ENABLE_HLSL?
+
+		-DPython3_EXECUTABLE="${PYTHON}"
+	)
+
+	if ! use elibc_musl; then
+		mycmakeargs+=(
+			-DPPC_LINUX_DEFAULT_IEEELONGDOUBLE=$(usex ieee-long-double)
+		)
+	fi
+
+	use test && mycmakeargs+=(
+		-DLLVM_BUILD_TESTS=ON
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	if multilib_is_native_abi; then
+		local build_docs=OFF
+		if llvm_are_manpages_built; then
+			build_docs=ON
+			mycmakeargs+=(
+				-DLLVM_BUILD_DOCS=ON
+				-DLLVM_ENABLE_SPHINX=ON
+				-DCLANG_INSTALL_SPHINX_HTML_DIR="${EPREFIX}/usr/share/doc/${PF}/html"
+				-DSPHINX_WARNINGS_AS_ERRORS=OFF
+			)
+			if use extra; then
+				mycmakeargs+=(
+					-DCLANG-TOOLS_INSTALL_SPHINX_HTML_DIR="${EPREFIX}/usr/share/doc/${PF}/tools-extra"
+				)
+			fi
+		fi
+		mycmakeargs+=(
+			-DCLANG_INCLUDE_DOCS=${build_docs}
+		)
+	fi
+	if multilib_native_use extra; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_CLANG_TOOLS_EXTRA_SOURCE_DIR="${WORKDIR}"/clang-tools-extra
+			-DCLANG_TOOLS_EXTRA_INCLUDE_DOCS=${build_docs}
+		)
+	else
+		mycmakeargs+=(
+			-DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF
+		)
+	fi
+
+	if [[ -n ${EPREFIX} ]]; then
+		mycmakeargs+=(
+			-DGCC_INSTALL_PREFIX="${EPREFIX}/usr"
+		)
+	fi
+
+	if tc-is-cross-compiler; then
+		has_version -b sys-devel/clang:${LLVM_MAJOR} ||
+			die "sys-devel/clang:${LLVM_MAJOR} is required on the build host."
+		local tools_bin=${BROOT}/usr/lib/llvm/${LLVM_MAJOR}/bin
+		mycmakeargs+=(
+			-DLLVM_TOOLS_BINARY_DIR="${tools_bin}"
+			-DCLANG_TABLEGEN="${tools_bin}"/clang-tblgen
+		)
+	fi
+
+	# LLVM can have very high memory consumption while linking,
+	# exhausting the limit on 32-bit linker executable
+	use x86 && local -x LDFLAGS="${LDFLAGS} -Wl,--no-keep-memory"
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+	cmake_src_configure
+
+	multilib_is_native_abi && check_distribution_components
+}
+
+multilib_src_compile() {
+	cmake_build distribution
+}
+
+multilib_src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	local test_targets=( check-clang )
+	if multilib_native_use extra; then
+		test_targets+=(
+			check-clang-tools
+			check-clangd
+		)
+	fi
+	cmake_build "${test_targets[@]}"
+}
+
+src_install() {
+	MULTILIB_WRAPPED_HEADERS=(
+		/usr/include/clang/Config/config.h
+	)
+
+	multilib-minimal_src_install
+
+	# Move runtime headers to /usr/lib/clang, where they belong
+	mv "${ED}"/usr/include/clangrt "${ED}"/usr/lib/clang || die
+	# move (remaining) wrapped headers back
+	if use extra; then
+		mv "${T}"/clang-tidy "${ED}"/usr/include/ || die
+	fi
+	mv "${ED}"/usr/include "${ED}"/usr/lib/llvm/${LLVM_MAJOR}/include || die
+
+	# Apply CHOST and version suffix to clang tools
+	local clang_tools=( clang clang++ clang-cl clang-cpp )
+	local abi i
+
+	# cmake gives us:
+	# - clang-X
+	# - clang -> clang-X
+	# - clang++, clang-cl, clang-cpp -> clang
+	# we want to have:
+	# - clang-X
+	# - clang++-X, clang-cl-X, clang-cpp-X -> clang-X
+	# - clang, clang++, clang-cl, clang-cpp -> clang*-X
+	# also in CHOST variant
+	for i in "${clang_tools[@]:1}"; do
+		rm "${ED}/usr/lib/llvm/${LLVM_MAJOR}/bin/${i}" || die
+		dosym "clang-${LLVM_MAJOR}" "/usr/lib/llvm/${LLVM_MAJOR}/bin/${i}-${LLVM_MAJOR}"
+		dosym "${i}-${LLVM_MAJOR}" "/usr/lib/llvm/${LLVM_MAJOR}/bin/${i}"
+	done
+
+	# now create target symlinks for all supported ABIs
+	for abi in $(get_all_abis); do
+		local abi_chost=$(get_abi_CHOST "${abi}")
+		for i in "${clang_tools[@]}"; do
+			dosym "${i}-${LLVM_MAJOR}" \
+				"/usr/lib/llvm/${LLVM_MAJOR}/bin/${abi_chost}-${i}-${LLVM_MAJOR}"
+			dosym "${abi_chost}-${i}-${LLVM_MAJOR}" \
+				"/usr/lib/llvm/${LLVM_MAJOR}/bin/${abi_chost}-${i}"
+		done
+	done
+}
+
+multilib_src_install() {
+	DESTDIR=${D} cmake_build install-distribution
+
+	# move headers to /usr/include for wrapping & ABI mismatch checks
+	# (also drop the version suffix from runtime headers)
+	rm -rf "${ED}"/usr/include || die
+	mv "${ED}"/usr/lib/llvm/${LLVM_MAJOR}/include "${ED}"/usr/include || die
+	mv "${ED}"/usr/lib/clang "${ED}"/usr/include/clangrt || die
+	if multilib_native_use extra; then
+		# don't wrap clang-tidy headers, the list is too long
+		# (they're fine for non-native ABI but enabling the targets is problematic)
+		mv "${ED}"/usr/include/clang-tidy "${T}/" || die
+	fi
+}
+
+multilib_src_install_all() {
+	python_fix_shebang "${ED}"
+	if use static-analyzer; then
+		python_optimize "${ED}"/usr/lib/llvm/${LLVM_MAJOR}/share/scan-view
+	fi
+
+	docompress "/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+	llvm_install_manpages
+	# match 'html' non-compression
+	use doc && docompress -x "/usr/share/doc/${PF}/tools-extra"
+	# +x for some reason; TODO: investigate
+	use static-analyzer && fperms a-x "/usr/lib/llvm/${LLVM_MAJOR}/share/man/man1/scan-build.1"
+}
+
+pkg_postinst() {
+	if [[ -z ${ROOT} && -f ${EPREFIX}/usr/share/eselect/modules/compiler-shadow.eselect ]] ; then
+		eselect compiler-shadow update all
+	fi
+
+	elog "You can find additional utility scripts in:"
+	elog "  ${EROOT}/usr/lib/llvm/${LLVM_MAJOR}/share/clang"
+	if use extra; then
+		elog "Some of them are vim integration scripts (with instructions inside)."
+		elog "The run-clang-tidy.py script requires the following additional package:"
+		elog "  dev-python/pyyaml"
+	fi
+}
+
+pkg_postrm() {
+	if [[ -z ${ROOT} && -f ${EPREFIX}/usr/share/eselect/modules/compiler-shadow.eselect ]] ; then
+		eselect compiler-shadow clean all
+	fi
+}
diff --git a/sys-devel/lld-toolchain-symlinks/lld-toolchain-symlinks-18.ebuild b/sys-devel/lld-toolchain-symlinks/lld-toolchain-symlinks-18.ebuild
index 3dcf9742c7a5..ce8f3f7900ef 100644
--- a/sys-devel/lld-toolchain-symlinks/lld-toolchain-symlinks-18.ebuild
+++ b/sys-devel/lld-toolchain-symlinks/lld-toolchain-symlinks-18.ebuild
@@ -11,7 +11,7 @@ S=${WORKDIR}
 
 LICENSE="public-domain"
 SLOT="${PV}"
-KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv ~sparc x86 ~arm64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv sparc x86 ~arm64-macos"
 IUSE="multilib-symlinks +native-symlinks"
 
 RDEPEND="
diff --git a/sys-devel/lld-toolchain-symlinks/lld-toolchain-symlinks-20.ebuild b/sys-devel/lld-toolchain-symlinks/lld-toolchain-symlinks-20.ebuild
new file mode 100644
index 000000000000..b85bf912c557
--- /dev/null
+++ b/sys-devel/lld-toolchain-symlinks/lld-toolchain-symlinks-20.ebuild
@@ -0,0 +1,37 @@
+# Copyright 2022-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit multilib
+
+DESCRIPTION="Symlinks to use LLD on binutils-free system"
+HOMEPAGE="https://wiki.gentoo.org/wiki/Project:LLVM"
+S=${WORKDIR}
+
+LICENSE="public-domain"
+SLOT="${PV}"
+IUSE="multilib-symlinks +native-symlinks"
+
+RDEPEND="
+	sys-devel/lld:${SLOT}
+"
+
+src_install() {
+	use native-symlinks || return
+
+	local chosts=( "${CHOST}" )
+	if use multilib-symlinks; then
+		local abi
+		for abi in $(get_all_abis); do
+			chosts+=( "$(get_abi_CHOST "${abi}")" )
+		done
+	fi
+
+	local dest=/usr/lib/llvm/${SLOT}/bin
+	dodir "${dest}"
+	dosym ld.lld "${dest}/ld"
+	for chost in "${chosts[@]}"; do
+		dosym ld.lld "${dest}/${chost}-ld"
+	done
+}
diff --git a/sys-devel/lld/lld-18.1.8.ebuild b/sys-devel/lld/lld-18.1.8.ebuild
index dade61281314..b220b6b78bc8 100644
--- a/sys-devel/lld/lld-18.1.8.ebuild
+++ b/sys-devel/lld/lld-18.1.8.ebuild
@@ -11,7 +11,7 @@ HOMEPAGE="https://llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
 SLOT="${LLVM_MAJOR}/${LLVM_SOABI}"
-KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv ~sparc x86 ~arm64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv sparc x86 ~arm64-macos"
 IUSE="debug test zstd"
 RESTRICT="!test? ( test )"
 
diff --git a/sys-devel/lld/lld-20.0.0.9999.ebuild b/sys-devel/lld/lld-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..79558afa1abe
--- /dev/null
+++ b/sys-devel/lld/lld-20.0.0.9999.ebuild
@@ -0,0 +1,93 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake flag-o-matic llvm.org llvm-utils python-any-r1 toolchain-funcs
+
+DESCRIPTION="The LLVM linker (link editor)"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="${LLVM_MAJOR}/${LLVM_SOABI}"
+IUSE="+debug test zstd"
+RESTRICT="!test? ( test )"
+
+DEPEND="
+	~sys-devel/llvm-${PV}[debug=,zstd=]
+	sys-libs/zlib:=
+	zstd? ( app-arch/zstd:= )
+"
+RDEPEND="
+	${DEPEND}
+	!sys-devel/lld:0
+"
+BDEPEND="
+	sys-devel/llvm:${LLVM_MAJOR}
+	test? (
+		$(python_gen_any_dep ">=dev-python/lit-${PV}[\${PYTHON_USEDEP}]")
+	)
+"
+PDEPEND="
+	>=sys-devel/lld-toolchain-symlinks-16-r2:${LLVM_MAJOR}
+"
+
+LLVM_COMPONENTS=( lld cmake libunwind/include/mach-o )
+llvm.org_set_globals
+
+python_check_deps() {
+	python_has_version ">=dev-python/lit-${PV}[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	use test && python-any-r1_pkg_setup
+}
+
+src_unpack() {
+	llvm.org_src_unpack
+
+	# Directory ${WORKDIR}/llvm does not exist with USE="-test",
+	# but LLVM_MAIN_SRC_DIR="${WORKDIR}/llvm" is set below,
+	# and ${LLVM_MAIN_SRC_DIR}/../libunwind/include is used by build system
+	# (lld/MachO/CMakeLists.txt) and is expected to be resolvable
+	# to existent directory ${WORKDIR}/libunwind/include.
+	mkdir -p "${WORKDIR}/llvm" || die
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# ODR violations (https://github.com/llvm/llvm-project/issues/83529, bug #922353)
+	filter-lto
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+
+	use elibc_musl && append-ldflags -Wl,-z,stack-size=2097152
+
+	local mycmakeargs=(
+		-DCMAKE_INSTALL_PREFIX="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}"
+		-DBUILD_SHARED_LIBS=ON
+		-DLLVM_INCLUDE_TESTS=$(usex test)
+		-DLLVM_ENABLE_ZLIB=FORCE_ON
+		-DLLVM_ENABLE_ZSTD=$(usex zstd FORCE_ON OFF)
+	)
+
+	use test && mycmakeargs+=(
+		-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+		-DPython3_EXECUTABLE="${PYTHON}"
+	)
+
+	tc-is-cross-compiler &&	mycmakeargs+=(
+		-DLLVM_TABLEGEN_EXE="${BROOT}/usr/lib/llvm/${LLVM_MAJOR}/bin/llvm-tblgen"
+	)
+
+	cmake_src_configure
+}
+
+src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-lld
+}
diff --git a/sys-devel/llvm-common/llvm-common-18.1.8.ebuild b/sys-devel/llvm-common/llvm-common-18.1.8.ebuild
index 976860dcd480..7bc053474801 100644
--- a/sys-devel/llvm-common/llvm-common-18.1.8.ebuild
+++ b/sys-devel/llvm-common/llvm-common-18.1.8.ebuild
@@ -10,7 +10,7 @@ HOMEPAGE="https://llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
 SLOT="0"
-KEYWORDS="amd64 arm arm64 ~loong ~mips ppc ppc64 ~riscv ~sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ~mips ppc ppc64 ~riscv sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
 IUSE="emacs"
 
 RDEPEND="
diff --git a/sys-devel/llvm-common/llvm-common-20.0.0.9999.ebuild b/sys-devel/llvm-common/llvm-common-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..2d8f35a84179
--- /dev/null
+++ b/sys-devel/llvm-common/llvm-common-20.0.0.9999.ebuild
@@ -0,0 +1,53 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit elisp-common llvm.org
+
+DESCRIPTION="Common files shared between multiple slots of LLVM"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0"
+IUSE="emacs"
+
+RDEPEND="
+	!sys-devel/llvm:0
+"
+BDEPEND="
+	emacs? ( >=app-editors/emacs-23.1:* )
+"
+
+LLVM_COMPONENTS=( llvm/utils )
+llvm.org_set_globals
+
+SITEFILE="50llvm-gentoo.el"
+BYTECOMPFLAGS="-L emacs"
+
+src_compile() {
+	default
+
+	use emacs && elisp-compile emacs/*.el
+}
+
+src_install() {
+	insinto /usr/share/vim/vimfiles
+	doins -r vim/*/
+	# some users may find it useful
+	newdoc vim/README README.vim
+	dodoc vim/vimrc
+
+	if use emacs ; then
+		elisp-install llvm emacs/*.{el,elc}
+		elisp-make-site-file "${SITEFILE}" llvm
+	fi
+}
+
+pkg_postinst() {
+	use emacs && elisp-site-regen
+}
+
+pkg_postrm() {
+	use emacs && elisp-site-regen
+}
diff --git a/sys-devel/llvm-toolchain-symlinks/llvm-toolchain-symlinks-18.ebuild b/sys-devel/llvm-toolchain-symlinks/llvm-toolchain-symlinks-18.ebuild
index 1c8bca695ee2..c1c22114f553 100644
--- a/sys-devel/llvm-toolchain-symlinks/llvm-toolchain-symlinks-18.ebuild
+++ b/sys-devel/llvm-toolchain-symlinks/llvm-toolchain-symlinks-18.ebuild
@@ -11,7 +11,7 @@ S=${WORKDIR}
 
 LICENSE="public-domain"
 SLOT="${PV}"
-KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv ~sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ppc ppc64 ~riscv sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
 IUSE="multilib-symlinks +native-symlinks"
 
 RDEPEND="
diff --git a/sys-devel/llvm-toolchain-symlinks/llvm-toolchain-symlinks-20.ebuild b/sys-devel/llvm-toolchain-symlinks/llvm-toolchain-symlinks-20.ebuild
new file mode 100644
index 000000000000..a57062acab8c
--- /dev/null
+++ b/sys-devel/llvm-toolchain-symlinks/llvm-toolchain-symlinks-20.ebuild
@@ -0,0 +1,46 @@
+# Copyright 2022-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit multilib
+
+DESCRIPTION="Symlinks to use LLVM on binutils-free system"
+HOMEPAGE="https://wiki.gentoo.org/wiki/Project:LLVM"
+S=${WORKDIR}
+
+LICENSE="public-domain"
+SLOT="${PV}"
+IUSE="multilib-symlinks +native-symlinks"
+
+RDEPEND="
+	sys-devel/llvm:${SLOT}
+"
+
+src_install() {
+	use native-symlinks || return
+
+	local tools=(
+		addr2line ar dlltool nm objcopy objdump ranlib readelf size
+		strings strip windres
+	)
+	local chosts=( "${CHOST}" )
+	if use multilib-symlinks; then
+		local abi
+		for abi in $(get_all_abis); do
+			chosts+=( "$(get_abi_CHOST "${abi}")" )
+		done
+	fi
+
+	local chost t
+	local dest=/usr/lib/llvm/${SLOT}/bin
+	dodir "${dest}"
+	for t in "${tools[@]}"; do
+		dosym "llvm-${t}" "${dest}/${t}"
+	done
+	for chost in "${chosts[@]}"; do
+		for t in "${tools[@]}"; do
+			dosym "llvm-${t}" "${dest}/${chost}-${t}"
+		done
+	done
+}
diff --git a/sys-devel/llvm/llvm-18.1.8-r1.ebuild b/sys-devel/llvm/llvm-18.1.8-r1.ebuild
index 408c29347fd4..30440d3d4cb5 100644
--- a/sys-devel/llvm/llvm-18.1.8-r1.ebuild
+++ b/sys-devel/llvm/llvm-18.1.8-r1.ebuild
@@ -19,7 +19,7 @@ HOMEPAGE="https://llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA BSD public-domain rc"
 SLOT="${LLVM_MAJOR}/${LLVM_SOABI}"
-KEYWORDS="amd64 arm arm64 ~loong ~mips ppc ppc64 ~riscv ~sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ~mips ppc ppc64 ~riscv sparc x86 ~amd64-linux ~arm64-macos ~ppc-macos ~x64-macos"
 IUSE="
 	+binutils-plugin debug debuginfod doc exegesis libedit +libffi
 	ncurses test xml z3 zstd
diff --git a/sys-devel/llvm/llvm-20.0.0.9999.ebuild b/sys-devel/llvm/llvm-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..c4930d262794
--- /dev/null
+++ b/sys-devel/llvm/llvm-20.0.0.9999.ebuild
@@ -0,0 +1,542 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+
+inherit cmake flag-o-matic llvm.org multilib-minimal pax-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="Low Level Virtual Machine"
+HOMEPAGE="https://llvm.org/"
+
+# Additional licenses:
+# 1. OpenBSD regex: Henry Spencer's license ('rc' in Gentoo) + BSD.
+# 2. xxhash: BSD.
+# 3. MD5 code: public-domain.
+# 4. ConvertUTF.h: TODO.
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA BSD public-domain rc"
+SLOT="${LLVM_MAJOR}/${LLVM_SOABI}"
+IUSE="
+	+binutils-plugin +debug debuginfod doc exegesis libedit +libffi
+	test xml z3 zstd
+"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	sys-libs/zlib:0=[${MULTILIB_USEDEP}]
+	debuginfod? (
+		net-misc/curl:=
+		dev-cpp/cpp-httplib:=
+	)
+	exegesis? ( dev-libs/libpfm:= )
+	libedit? ( dev-libs/libedit:0=[${MULTILIB_USEDEP}] )
+	libffi? ( >=dev-libs/libffi-3.0.13-r1:0=[${MULTILIB_USEDEP}] )
+	xml? ( dev-libs/libxml2:2=[${MULTILIB_USEDEP}] )
+	z3? ( >=sci-mathematics/z3-4.7.1:0=[${MULTILIB_USEDEP}] )
+	zstd? ( app-arch/zstd:=[${MULTILIB_USEDEP}] )
+"
+DEPEND="
+	${RDEPEND}
+	binutils-plugin? ( sys-libs/binutils-libs )
+"
+BDEPEND="
+	${PYTHON_DEPS}
+	dev-lang/perl
+	sys-devel/gnuconfig
+	kernel_Darwin? (
+		<sys-libs/libcxx-${LLVM_VERSION}.9999
+	)
+	libffi? ( virtual/pkgconfig )
+"
+# There are no file collisions between these versions but having :0
+# installed means llvm-config there will take precedence.
+RDEPEND="
+	${RDEPEND}
+	!sys-devel/llvm:0
+"
+PDEPEND="
+	sys-devel/llvm-common
+	sys-devel/llvm-toolchain-symlinks:${LLVM_MAJOR}
+	binutils-plugin? ( >=sys-devel/llvmgold-${LLVM_MAJOR} )
+"
+
+LLVM_COMPONENTS=( llvm cmake third-party )
+LLVM_MANPAGES=1
+LLVM_USE_TARGETS=provide
+llvm.org_set_globals
+
+[[ -n ${LLVM_MANPAGE_DIST} ]] && BDEPEND+=" doc? ( "
+BDEPEND+="
+	$(python_gen_any_dep '
+		dev-python/myst-parser[${PYTHON_USEDEP}]
+		dev-python/sphinx[${PYTHON_USEDEP}]
+	')
+"
+[[ -n ${LLVM_MANPAGE_DIST} ]] && BDEPEND+=" ) "
+
+python_check_deps() {
+	llvm_are_manpages_built || return 0
+
+	python_has_version -b "dev-python/myst-parser[${PYTHON_USEDEP}]" &&
+	python_has_version -b "dev-python/sphinx[${PYTHON_USEDEP}]"
+}
+
+check_uptodate() {
+	local prod_targets=(
+		$(sed -n -e '/set(LLVM_ALL_TARGETS/,/)/p' CMakeLists.txt \
+			| tail -n +2 | head -n -1)
+	)
+	local all_targets=(
+		lib/Target/*/
+	)
+	all_targets=( "${all_targets[@]#lib/Target/}" )
+	all_targets=( "${all_targets[@]%/}" )
+
+	local exp_targets=() i
+	for i in "${all_targets[@]}"; do
+		has "${i}" "${prod_targets[@]}" || exp_targets+=( "${i}" )
+	done
+
+	if [[ ${exp_targets[*]} != ${ALL_LLVM_EXPERIMENTAL_TARGETS[*]} ]]; then
+		eqawarn "ALL_LLVM_EXPERIMENTAL_TARGETS is outdated!"
+		eqawarn "    Have: ${ALL_LLVM_EXPERIMENTAL_TARGETS[*]}"
+		eqawarn "Expected: ${exp_targets[*]}"
+		eqawarn
+	fi
+
+	if [[ ${prod_targets[*]} != ${ALL_LLVM_PRODUCTION_TARGETS[*]} ]]; then
+		eqawarn "ALL_LLVM_PRODUCTION_TARGETS is outdated!"
+		eqawarn "    Have: ${ALL_LLVM_PRODUCTION_TARGETS[*]}"
+		eqawarn "Expected: ${prod_targets[*]}"
+	fi
+}
+
+check_distribution_components() {
+	if [[ ${CMAKE_MAKEFILE_GENERATOR} == ninja ]]; then
+		local all_targets=() my_targets=() l
+		cd "${BUILD_DIR}" || die
+
+		while read -r l; do
+			if [[ ${l} == install-*-stripped:* ]]; then
+				l=${l#install-}
+				l=${l%%-stripped*}
+
+				case ${l} in
+					# shared libs
+					LLVM|LLVMgold)
+						;;
+					# TableGen lib + deps
+					LLVMDemangle|LLVMSupport|LLVMTableGen)
+						;;
+					# used by lldb
+					LLVMDebuginfod)
+						;;
+					# testing libraries
+					LLVMTestingAnnotations|LLVMTestingSupport)
+						;;
+					# static libs
+					LLVM*)
+						continue
+						;;
+					# meta-targets
+					distribution|llvm-libraries)
+						continue
+						;;
+					# used only w/ USE=doc
+					docs-llvm-html)
+						use doc || continue
+						;;
+				esac
+
+				all_targets+=( "${l}" )
+			fi
+		done < <(${NINJA} -t targets all)
+
+		while read -r l; do
+			my_targets+=( "${l}" )
+		done < <(get_distribution_components $"\n")
+
+		local add=() remove=()
+		for l in "${all_targets[@]}"; do
+			if ! has "${l}" "${my_targets[@]}"; then
+				add+=( "${l}" )
+			fi
+		done
+		for l in "${my_targets[@]}"; do
+			if ! has "${l}" "${all_targets[@]}"; then
+				remove+=( "${l}" )
+			fi
+		done
+
+		if [[ ${#add[@]} -gt 0 || ${#remove[@]} -gt 0 ]]; then
+			eqawarn "get_distribution_components() is outdated!"
+			eqawarn "   Add: ${add[*]}"
+			eqawarn "Remove: ${remove[*]}"
+		fi
+		cd - >/dev/null || die
+	fi
+}
+
+src_prepare() {
+	# disable use of SDK on OSX, bug #568758
+	sed -i -e 's/xcrun/false/' utils/lit/lit/util.py || die
+
+	# Update config.guess to support more systems
+	cp "${BROOT}/usr/share/gnuconfig/config.guess" cmake/ || die
+
+	# Verify that the ebuild is up-to-date
+	check_uptodate
+
+	llvm.org_src_prepare
+}
+
+get_distribution_components() {
+	local sep=${1-;}
+
+	local out=(
+		# shared libs
+		LLVM
+		LTO
+		Remarks
+
+		# tools
+		llvm-config
+
+		# common stuff
+		cmake-exports
+		llvm-headers
+
+		# libraries needed for clang-tblgen
+		LLVMDemangle
+		LLVMSupport
+		LLVMTableGen
+
+		# testing libraries
+		llvm_gtest
+		llvm_gtest_main
+		LLVMTestingAnnotations
+		LLVMTestingSupport
+	)
+
+	if multilib_is_native_abi; then
+		out+=(
+			# library used by lldb
+			LLVMDebuginfod
+
+			# utilities
+			llvm-tblgen
+			FileCheck
+			llvm-PerfectShuffle
+			count
+			not
+			yaml-bench
+			UnicodeNameMappingGenerator
+
+			# tools
+			bugpoint
+			dsymutil
+			llc
+			lli
+			lli-child-target
+			llvm-addr2line
+			llvm-ar
+			llvm-as
+			llvm-bcanalyzer
+			llvm-bitcode-strip
+			llvm-c-test
+			llvm-cat
+			llvm-cfi-verify
+			llvm-config
+			llvm-cov
+			llvm-cvtres
+			llvm-cxxdump
+			llvm-cxxfilt
+			llvm-cxxmap
+			llvm-debuginfo-analyzer
+			llvm-debuginfod-find
+			llvm-diff
+			llvm-dis
+			llvm-dlltool
+			llvm-dwarfdump
+			llvm-dwarfutil
+			llvm-dwp
+			llvm-exegesis
+			llvm-extract
+			llvm-gsymutil
+			llvm-ifs
+			llvm-install-name-tool
+			llvm-jitlink
+			llvm-jitlink-executor
+			llvm-lib
+			llvm-libtool-darwin
+			llvm-link
+			llvm-lipo
+			llvm-lto
+			llvm-lto2
+			llvm-mc
+			llvm-mca
+			llvm-ml
+			llvm-modextract
+			llvm-mt
+			llvm-nm
+			llvm-objcopy
+			llvm-objdump
+			llvm-opt-report
+			llvm-otool
+			llvm-pdbutil
+			llvm-profdata
+			llvm-profgen
+			llvm-ranlib
+			llvm-rc
+			llvm-readelf
+			llvm-readobj
+			llvm-readtapi
+			llvm-reduce
+			llvm-remarkutil
+			llvm-rtdyld
+			llvm-sim
+			llvm-size
+			llvm-split
+			llvm-stress
+			llvm-strings
+			llvm-strip
+			llvm-symbolizer
+			llvm-tli-checker
+			llvm-undname
+			llvm-windres
+			llvm-xray
+			obj2yaml
+			opt
+			reduce-chunk-list
+			sancov
+			sanstats
+			split-file
+			verify-uselistorder
+			yaml2obj
+
+			# python modules
+			opt-viewer
+		)
+
+		if llvm_are_manpages_built; then
+			out+=(
+				# manpages
+				docs-dsymutil-man
+				docs-llvm-dwarfdump-man
+				docs-llvm-man
+			)
+		fi
+		use doc && out+=(
+			docs-llvm-html
+		)
+
+		use binutils-plugin && out+=(
+			LLVMgold
+		)
+		use debuginfod && out+=(
+			llvm-debuginfod
+		)
+	fi
+
+	printf "%s${sep}" "${out[@]}"
+}
+
+multilib_src_configure() {
+	if use ppc && tc-is-gcc && [[ $(gcc-major-version) -lt 14 ]]; then
+		# Workaround for bug #880677
+		append-flags $(test-flags-CXX -fno-ipa-sra -fno-ipa-modref -fno-ipa-icf)
+	fi
+
+	# ODR violations (bug #917536, bug #926529). Just do it for GCC for now
+	# to avoid people grumbling. GCC is, anecdotally, more likely to miscompile
+	# LLVM with LTO anyway (which is not necessarily its fault).
+	tc-is-gcc && filter-lto
+
+	local ffi_cflags ffi_ldflags
+	if use libffi; then
+		ffi_cflags=$($(tc-getPKG_CONFIG) --cflags-only-I libffi)
+		ffi_ldflags=$($(tc-getPKG_CONFIG) --libs-only-L libffi)
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		# disable appending VCS revision to the version to improve
+		# direct cache hit ratio
+		-DLLVM_APPEND_VC_REV=OFF
+		-DCMAKE_INSTALL_PREFIX="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}"
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DBUILD_SHARED_LIBS=OFF
+		-DLLVM_BUILD_LLVM_DYLIB=ON
+		-DLLVM_LINK_LLVM_DYLIB=ON
+		-DLLVM_DISTRIBUTION_COMPONENTS=$(get_distribution_components)
+
+		# cheap hack: LLVM combines both anyway, and the only difference
+		# is that the former list is explicitly verified at cmake time
+		-DLLVM_TARGETS_TO_BUILD=""
+		-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD="${LLVM_TARGETS// /;}"
+		-DLLVM_INCLUDE_BENCHMARKS=OFF
+		-DLLVM_INCLUDE_TESTS=ON
+		-DLLVM_BUILD_TESTS=$(usex test)
+		-DLLVM_INSTALL_GTEST=ON
+
+		-DLLVM_ENABLE_FFI=$(usex libffi)
+		-DLLVM_ENABLE_LIBEDIT=$(usex libedit)
+		-DLLVM_ENABLE_LIBXML2=$(usex xml)
+		-DLLVM_ENABLE_ASSERTIONS=$(usex debug)
+		-DLLVM_ENABLE_LIBPFM=$(usex exegesis)
+		-DLLVM_ENABLE_EH=ON
+		-DLLVM_ENABLE_RTTI=ON
+		-DLLVM_ENABLE_Z3_SOLVER=$(usex z3)
+		-DLLVM_ENABLE_ZLIB=FORCE_ON
+		-DLLVM_ENABLE_ZSTD=$(usex zstd FORCE_ON OFF)
+		-DLLVM_ENABLE_CURL=$(usex debuginfod)
+		-DLLVM_ENABLE_HTTPLIB=$(usex debuginfod)
+
+		-DLLVM_HOST_TRIPLE="${CHOST}"
+
+		-DFFI_INCLUDE_DIR="${ffi_cflags#-I}"
+		-DFFI_LIBRARY_DIR="${ffi_ldflags#-L}"
+
+		-DPython3_EXECUTABLE="${PYTHON}"
+
+		# disable OCaml bindings (now in dev-ml/llvm-ocaml)
+		-DOCAMLFIND=NO
+	)
+
+	local suffix=
+	if [[ -n ${EGIT_VERSION} && ${EGIT_BRANCH} != release/* ]]; then
+		# the ABI of the main branch is not stable, so let's include
+		# the commit id in the SOVERSION to contain the breakage
+		suffix+="git${EGIT_VERSION::8}"
+	fi
+	if [[ $(tc-get-cxx-stdlib) == libc++ ]]; then
+		# Smart hack: alter version suffix -> SOVERSION when linking
+		# against libc++. This way we won't end up mixing LLVM libc++
+		# libraries with libstdc++ clang, and the other way around.
+		suffix+="+libcxx"
+		mycmakeargs+=(
+			-DLLVM_ENABLE_LIBCXX=ON
+		)
+	fi
+	mycmakeargs+=(
+		-DLLVM_VERSION_SUFFIX="${suffix}"
+	)
+
+	use test && mycmakeargs+=(
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	if multilib_is_native_abi; then
+		local build_docs=OFF
+		if llvm_are_manpages_built; then
+			build_docs=ON
+			mycmakeargs+=(
+				-DCMAKE_INSTALL_MANDIR="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+				-DLLVM_INSTALL_SPHINX_HTML_DIR="${EPREFIX}/usr/share/doc/${PF}/html"
+				-DSPHINX_WARNINGS_AS_ERRORS=OFF
+			)
+		fi
+
+		mycmakeargs+=(
+			-DLLVM_BUILD_DOCS=${build_docs}
+			-DLLVM_ENABLE_OCAMLDOC=OFF
+			-DLLVM_ENABLE_SPHINX=${build_docs}
+			-DLLVM_ENABLE_DOXYGEN=OFF
+			-DLLVM_INSTALL_UTILS=ON
+		)
+		use binutils-plugin && mycmakeargs+=(
+			-DLLVM_BINUTILS_INCDIR="${EPREFIX}"/usr/include
+		)
+	fi
+
+	use kernel_Darwin && mycmakeargs+=(
+		# Use our libtool instead of looking it up with xcrun
+		-DCMAKE_LIBTOOL="${EPREFIX}/usr/bin/${CHOST}-libtool"
+	)
+
+	# LLVM can have very high memory consumption while linking,
+	# exhausting the limit on 32-bit linker executable
+	use x86 && local -x LDFLAGS="${LDFLAGS} -Wl,--no-keep-memory"
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+	cmake_src_configure
+
+	grep -q -E "^CMAKE_PROJECT_VERSION_MAJOR(:.*)?=${LLVM_MAJOR}$" \
+			CMakeCache.txt ||
+		die "Incorrect version, did you update _LLVM_MAIN_MAJOR?"
+	multilib_is_native_abi && check_distribution_components
+}
+
+multilib_src_compile() {
+	tc-env_build cmake_build distribution
+
+	pax-mark m "${BUILD_DIR}"/bin/llvm-rtdyld
+	pax-mark m "${BUILD_DIR}"/bin/lli
+	pax-mark m "${BUILD_DIR}"/bin/lli-child-target
+
+	if use test; then
+		pax-mark m "${BUILD_DIR}"/unittests/ExecutionEngine/Orc/OrcJITTests
+		pax-mark m "${BUILD_DIR}"/unittests/ExecutionEngine/MCJIT/MCJITTests
+		pax-mark m "${BUILD_DIR}"/unittests/Support/SupportTests
+	fi
+}
+
+multilib_src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check
+}
+
+src_install() {
+	local MULTILIB_CHOST_TOOLS=(
+		/usr/lib/llvm/${LLVM_MAJOR}/bin/llvm-config
+	)
+
+	local MULTILIB_WRAPPED_HEADERS=(
+		/usr/include/llvm/Config/llvm-config.h
+	)
+
+	local LLVM_LDPATHS=()
+	multilib-minimal_src_install
+
+	# move wrapped headers back
+	mv "${ED}"/usr/include "${ED}"/usr/lib/llvm/${LLVM_MAJOR}/include || die
+}
+
+multilib_src_install() {
+	DESTDIR=${D} cmake_build install-distribution
+
+	# move headers to /usr/include for wrapping
+	rm -rf "${ED}"/usr/include || die
+	mv "${ED}"/usr/lib/llvm/${LLVM_MAJOR}/include "${ED}"/usr/include || die
+
+	LLVM_LDPATHS+=( "${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/$(get_libdir)" )
+}
+
+multilib_src_install_all() {
+	local revord=$(( 9999 - ${LLVM_MAJOR} ))
+	newenvd - "60llvm-${revord}" <<-_EOF_
+		PATH="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin"
+		# we need to duplicate it in ROOTPATH for Portage to respect...
+		ROOTPATH="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin"
+		MANPATH="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+		LDPATH="$( IFS=:; echo "${LLVM_LDPATHS[*]}" )"
+	_EOF_
+
+	docompress "/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+	llvm_install_manpages
+}
+
+pkg_postinst() {
+	elog "You can find additional opt-viewer utility scripts in:"
+	elog "  ${EROOT}/usr/lib/llvm/${LLVM_MAJOR}/share/opt-viewer"
+	elog "To use these scripts, you will need Python along with the following"
+	elog "packages:"
+	elog "  dev-python/pygments (for opt-viewer)"
+	elog "  dev-python/pyyaml (for all of them)"
+}
diff --git a/sys-devel/llvmgold/llvmgold-18.ebuild b/sys-devel/llvmgold/llvmgold-18.ebuild
index 855ee96b0fe1..f59dbf8bd338 100644
--- a/sys-devel/llvmgold/llvmgold-18.ebuild
+++ b/sys-devel/llvmgold/llvmgold-18.ebuild
@@ -9,7 +9,7 @@ S=${WORKDIR}
 
 LICENSE="public-domain"
 SLOT="0"
-KEYWORDS="amd64 arm arm64 ~loong ~mips ~ppc ppc64 ~riscv ~sparc x86 ~amd64-linux"
+KEYWORDS="amd64 arm arm64 ~loong ~mips ~ppc ppc64 ~riscv sparc x86 ~amd64-linux"
 
 RDEPEND="
 	sys-devel/llvm:${PV}[binutils-plugin]
diff --git a/sys-devel/llvmgold/llvmgold-20.ebuild b/sys-devel/llvmgold/llvmgold-20.ebuild
new file mode 100644
index 000000000000..cc4a41d311fc
--- /dev/null
+++ b/sys-devel/llvmgold/llvmgold-20.ebuild
@@ -0,0 +1,22 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+DESCRIPTION="LLVMgold plugin symlink for autoloading"
+HOMEPAGE="https://llvm.org/"
+S=${WORKDIR}
+
+LICENSE="public-domain"
+SLOT="0"
+
+RDEPEND="
+	sys-devel/llvm:${PV}[binutils-plugin]
+	!sys-devel/llvm:0
+"
+
+src_install() {
+	dodir "/usr/${CHOST}/binutils-bin/lib/bfd-plugins"
+	dosym "../../../../lib/llvm/${PV}/$(get_libdir)/LLVMgold.so" \
+		"/usr/${CHOST}/binutils-bin/lib/bfd-plugins/LLVMgold.so"
+}
diff --git a/sys-libs/compiler-rt-sanitizers/compiler-rt-sanitizers-20.0.0.9999.ebuild b/sys-libs/compiler-rt-sanitizers/compiler-rt-sanitizers-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..d395b7fd5a11
--- /dev/null
+++ b/sys-libs/compiler-rt-sanitizers/compiler-rt-sanitizers-20.0.0.9999.ebuild
@@ -0,0 +1,220 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit check-reqs cmake flag-o-matic llvm.org llvm-utils python-any-r1
+
+DESCRIPTION="Compiler runtime libraries for clang (sanitizers & xray)"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="${LLVM_MAJOR}"
+IUSE="+abi_x86_32 abi_x86_64 +clang +debug test"
+# base targets
+IUSE+=" +ctx-profile +libfuzzer +memprof +orc +profile +xray"
+# sanitizer targets, keep in sync with config-ix.cmake
+# NB: ubsan, scudo deliberately match two entries
+SANITIZER_FLAGS=(
+	asan dfsan lsan msan hwasan tsan ubsan safestack cfi scudo
+	shadowcallstack gwp-asan
+)
+IUSE+=" ${SANITIZER_FLAGS[@]/#/+}"
+REQUIRED_USE="
+	|| ( ${SANITIZER_FLAGS[*]} libfuzzer orc profile xray )
+	test? (
+		cfi? ( ubsan )
+		gwp-asan? ( scudo )
+	)
+"
+RESTRICT="
+	!clang? ( test )
+	!test? ( test )
+"
+
+DEPEND="
+	sys-devel/llvm:${LLVM_MAJOR}
+	virtual/libcrypt[abi_x86_32(-)?,abi_x86_64(-)?]
+"
+BDEPEND="
+	clang? ( sys-devel/clang )
+	elibc_glibc? ( net-libs/libtirpc )
+	test? (
+		$(python_gen_any_dep ">=dev-python/lit-15[\${PYTHON_USEDEP}]")
+		=sys-devel/clang-${LLVM_VERSION}*:${LLVM_MAJOR}
+		sys-libs/compiler-rt:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+"
+
+LLVM_COMPONENTS=( compiler-rt cmake llvm/cmake )
+LLVM_TEST_COMPONENTS=(
+	llvm/include/llvm/ProfileData llvm/lib/Testing/Support third-party
+)
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version ">=dev-python/lit-15[${PYTHON_USEDEP}]"
+}
+
+check_space() {
+	if use test; then
+		local CHECKREQS_DISK_BUILD=11G
+		check-reqs_pkg_pretend
+	fi
+}
+
+pkg_pretend() {
+	check_space
+}
+
+pkg_setup() {
+	check_space
+	python-any-r1_pkg_setup
+}
+
+src_prepare() {
+	sed -i -e 's:-Werror::' lib/tsan/go/buildgo.sh || die
+
+	local flag
+	for flag in "${SANITIZER_FLAGS[@]}"; do
+		if ! use "${flag}"; then
+			local cmake_flag=${flag/-/_}
+			sed -i -e "/COMPILER_RT_HAS_${cmake_flag^^}/s:TRUE:FALSE:" \
+				cmake/config-ix.cmake || die
+		fi
+	done
+
+	# TODO: fix these tests to be skipped upstream
+	if use asan && ! use profile; then
+		rm test/asan/TestCases/asan_and_llvm_coverage_test.cpp || die
+	fi
+	if use ubsan && ! use cfi; then
+		> test/cfi/CMakeLists.txt || die
+	fi
+	# hangs, sigh
+	rm test/tsan/getline_nohang.cpp || die
+
+	llvm.org_src_prepare
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+
+	# pre-set since we need to pass it to cmake
+	BUILD_DIR=${WORKDIR}/compiler-rt_build
+
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	local flag want_sanitizer=OFF
+	for flag in "${SANITIZER_FLAGS[@]}"; do
+		if use "${flag}"; then
+			want_sanitizer=ON
+			break
+		fi
+	done
+
+	local mycmakeargs=(
+		-DCOMPILER_RT_INSTALL_PATH="${EPREFIX}/usr/lib/clang/${LLVM_MAJOR}"
+		# use a build dir structure consistent with install
+		# this makes it possible to easily deploy test-friendly clang
+		-DCOMPILER_RT_OUTPUT_DIR="${BUILD_DIR}/lib/clang/${LLVM_MAJOR}"
+
+		-DCOMPILER_RT_INCLUDE_TESTS=$(usex test)
+		# builtins & crt installed by sys-libs/compiler-rt
+		-DCOMPILER_RT_BUILD_BUILTINS=OFF
+		-DCOMPILER_RT_BUILD_CRT=OFF
+		-DCOMPILER_RT_BUILD_CTX_PROFILE=$(usex ctx-profile)
+		-DCOMPILER_RT_BUILD_LIBFUZZER=$(usex libfuzzer)
+		-DCOMPILER_RT_BUILD_MEMPROF=$(usex memprof)
+		-DCOMPILER_RT_BUILD_ORC=$(usex orc)
+		-DCOMPILER_RT_BUILD_PROFILE=$(usex profile)
+		-DCOMPILER_RT_BUILD_SANITIZERS="${want_sanitizer}"
+		-DCOMPILER_RT_BUILD_XRAY=$(usex xray)
+
+		-DPython3_EXECUTABLE="${PYTHON}"
+	)
+
+	if use amd64; then
+		mycmakeargs+=(
+			-DCAN_TARGET_i386=$(usex abi_x86_32)
+			-DCAN_TARGET_x86_64=$(usex abi_x86_64)
+		)
+	fi
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+
+			# they are created during src_test()
+			-DCOMPILER_RT_TEST_COMPILER="${BUILD_DIR}/lib/llvm/${LLVM_MAJOR}/bin/clang"
+			-DCOMPILER_RT_TEST_CXX_COMPILER="${BUILD_DIR}/lib/llvm/${LLVM_MAJOR}/bin/clang++"
+		)
+
+		# same flags are passed for build & tests, so we need to strip
+		# them down to a subset supported by clang
+		CC=${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin/clang \
+		CXX=${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin/clang++ \
+		strip-unsupported-flags
+	fi
+
+	if use prefix && [[ "${CHOST}" == *-darwin* ]] ; then
+		mycmakeargs+=(
+			# setting -isysroot is disabled with compiler-rt-prefix-paths.patch
+			# this allows adding arm64 support using SDK in EPREFIX
+			-DDARWIN_macosx_CACHED_SYSROOT="${EPREFIX}/MacOSX.sdk"
+			# Set version based on the SDK in EPREFIX
+			# This disables i386 for SDK >= 10.15
+			# Will error if has_use tsan and SDK < 10.12
+			-DDARWIN_macosx_OVERRIDE_SDK_VERSION="$(realpath ${EPREFIX}/MacOSX.sdk | sed -e 's/.*MacOSX\(.*\)\.sdk/\1/')"
+			# Use our libtool instead of looking it up with xcrun
+			-DCMAKE_LIBTOOL="${EPREFIX}/usr/bin/${CHOST}-libtool"
+		)
+	fi
+
+	cmake_src_configure
+
+	if use test; then
+		local sys_dir=( "${EPREFIX}"/usr/lib/clang/${LLVM_MAJOR}/lib/* )
+		[[ -e ${sys_dir} ]] || die "Unable to find ${sys_dir}"
+		[[ ${#sys_dir[@]} -eq 1 ]] || die "Non-deterministic compiler-rt install: ${sys_dir[*]}"
+
+		# copy clang over since resource_dir is located relatively to binary
+		# therefore, we can put our new libraries in it
+		mkdir -p "${BUILD_DIR}"/lib/{llvm/${LLVM_MAJOR}/{bin,$(get_libdir)},clang/${LLVM_MAJOR}/include} || die
+		cp "${EPREFIX}"/usr/lib/llvm/${LLVM_MAJOR}/bin/clang{,++} \
+			"${BUILD_DIR}"/lib/llvm/${LLVM_MAJOR}/bin/ || die
+		cp "${EPREFIX}"/usr/lib/clang/${LLVM_MAJOR}/include/*.h \
+			"${BUILD_DIR}"/lib/clang/${LLVM_MAJOR}/include/ || die
+		cp "${sys_dir}"/*builtins*.a \
+			"${BUILD_DIR}/lib/clang/${LLVM_MAJOR}/lib/${sys_dir##*/}/" || die
+		# we also need LLVMgold.so for gold-based tests
+		if [[ -f ${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/$(get_libdir)/LLVMgold.so ]]; then
+			ln -s "${EPREFIX}"/usr/lib/llvm/${LLVM_MAJOR}/$(get_libdir)/LLVMgold.so \
+				"${BUILD_DIR}"/lib/llvm/${LLVM_MAJOR}/$(get_libdir)/ || die
+		fi
+	fi
+}
+
+src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	# disable sandbox to have it stop clobbering LD_PRELOAD
+	local -x SANDBOX_ON=0
+	# wipe LD_PRELOAD to make ASAN happy
+	local -x LD_PRELOAD=
+
+	cmake_build check-all
+}
diff --git a/sys-libs/compiler-rt/compiler-rt-20.0.0.9999.ebuild b/sys-libs/compiler-rt/compiler-rt-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..ca99f4442636
--- /dev/null
+++ b/sys-libs/compiler-rt/compiler-rt-20.0.0.9999.ebuild
@@ -0,0 +1,173 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake crossdev flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="Compiler runtime library for clang (built-in part)"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="${LLVM_MAJOR}"
+IUSE="+abi_x86_32 abi_x86_64 +clang +debug test"
+RESTRICT="!test? ( test ) !clang? ( test )"
+
+DEPEND="
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? ( sys-devel/clang )
+	test? (
+		$(python_gen_any_dep ">=dev-python/lit-15[\${PYTHON_USEDEP}]")
+		=sys-devel/clang-${LLVM_VERSION}*:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+"
+
+LLVM_COMPONENTS=( compiler-rt cmake llvm/cmake )
+LLVM_TEST_COMPONENTS=( llvm/include/llvm/TargetParser )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version ">=dev-python/lit-15[${PYTHON_USEDEP}]"
+}
+
+pkg_pretend() {
+	if ! use clang && ! tc-is-clang; then
+		ewarn "Building using a compiler other than clang may result in broken atomics"
+		ewarn "library. Enable USE=clang unless you have a very good reason not to."
+	fi
+}
+
+pkg_setup() {
+	if target_is_not_host || tc-is-cross-compiler ; then
+		# strips vars like CFLAGS="-march=x86_64-v3" for non-x86 architectures
+		CHOST=${CTARGET} strip-unsupported-flags
+		# overrides host docs otherwise
+		DOCS=()
+	fi
+	python-any-r1_pkg_setup
+}
+
+test_compiler() {
+	target_is_not_host && return
+	$(tc-getCC) ${CFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+
+	# pre-set since we need to pass it to cmake
+	BUILD_DIR=${WORKDIR}/${P}_build
+
+	if use clang && ! is_crosspkg; then
+		# Only do this conditionally to allow overriding with
+		# e.g. CC=clang-13 in case of breakage
+		if ! tc-is-clang ; then
+			local -x CC=${CHOST}-clang
+			local -x CXX=${CHOST}-clang++
+		fi
+
+		strip-unsupported-flags
+	fi
+
+	if ! is_crosspkg && ! test_compiler ; then
+		local nolib_flags=( -nodefaultlibs -lc )
+
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CC} seems to lack runtime, trying with ${nolib_flags[*]}"
+		elif test_compiler "${nolib_flags[@]}" -nostartfiles; then
+			# Avoiding -nostartfiles earlier on for bug #862540,
+			# and set available entry symbol for bug #862798.
+			nolib_flags+=( -nostartfiles -e main )
+
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CC} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local mycmakeargs=(
+		-DCOMPILER_RT_INSTALL_PATH="${EPREFIX}/usr/lib/clang/${LLVM_MAJOR}"
+
+		-DCOMPILER_RT_INCLUDE_TESTS=$(usex test)
+		-DCOMPILER_RT_BUILD_CTX_PROFILE=OFF
+		-DCOMPILER_RT_BUILD_LIBFUZZER=OFF
+		-DCOMPILER_RT_BUILD_MEMPROF=OFF
+		-DCOMPILER_RT_BUILD_ORC=OFF
+		-DCOMPILER_RT_BUILD_PROFILE=OFF
+		-DCOMPILER_RT_BUILD_SANITIZERS=OFF
+		-DCOMPILER_RT_BUILD_XRAY=OFF
+
+		-DPython3_EXECUTABLE="${PYTHON}"
+	)
+
+	if use amd64 && ! target_is_not_host; then
+		mycmakeargs+=(
+			-DCAN_TARGET_i386=$(usex abi_x86_32)
+			-DCAN_TARGET_x86_64=$(usex abi_x86_64)
+		)
+	fi
+
+	if is_crosspkg; then
+		# Needed to target built libc headers
+		export CFLAGS="${CFLAGS} -isystem /usr/${CTARGET}/usr/include"
+		mycmakeargs+=(
+			# Without this, the compiler will compile a test program
+			# and fail due to no builtins.
+			-DCMAKE_C_COMPILER_WORKS=1
+			-DCMAKE_CXX_COMPILER_WORKS=1
+
+			# Without this, compiler-rt install location is not unique
+			# to target triples, only to architecture.
+			# Needed if you want to target multiple libcs for one arch.
+			-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON
+
+			-DCMAKE_ASM_COMPILER_TARGET="${CTARGET}"
+			-DCMAKE_C_COMPILER_TARGET="${CTARGET}"
+			-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON
+		)
+	fi
+
+	if use prefix && [[ "${CHOST}" == *-darwin* ]] ; then
+		mycmakeargs+=(
+			# setting -isysroot is disabled with compiler-rt-prefix-paths.patch
+			# this allows adding arm64 support using SDK in EPREFIX
+			-DDARWIN_macosx_CACHED_SYSROOT="${EPREFIX}/MacOSX.sdk"
+			# Set version based on the SDK in EPREFIX.
+			# This disables i386 for SDK >= 10.15
+			-DDARWIN_macosx_OVERRIDE_SDK_VERSION="$(realpath ${EPREFIX}/MacOSX.sdk | sed -e 's/.*MacOSX\(.*\)\.sdk/\1/')"
+			# Use our libtool instead of looking it up with xcrun
+			-DCMAKE_LIBTOOL="${EPREFIX}/usr/bin/${CHOST}-libtool"
+		)
+	fi
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+
+			-DCOMPILER_RT_TEST_COMPILER="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin/clang"
+			-DCOMPILER_RT_TEST_CXX_COMPILER="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin/clang++"
+		)
+	fi
+
+	cmake_src_configure
+}
+
+src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+
+	cmake_build check-builtins
+}
diff --git a/sys-libs/libcxx/libcxx-18.1.8.ebuild b/sys-libs/libcxx/libcxx-18.1.8.ebuild
index b6fec4c4d1af..372665da52df 100644
--- a/sys-libs/libcxx/libcxx-18.1.8.ebuild
+++ b/sys-libs/libcxx/libcxx-18.1.8.ebuild
@@ -12,7 +12,7 @@ HOMEPAGE="https://libcxx.llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
 SLOT="0"
-KEYWORDS="amd64 arm arm64 ~loong ~riscv ~sparc x86 ~arm64-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ~riscv sparc x86 ~arm64-macos ~x64-macos"
 IUSE="+clang +libcxxabi +static-libs test"
 REQUIRED_USE="test? ( clang )"
 RESTRICT="!test? ( test )"
diff --git a/sys-libs/libcxx/libcxx-20.0.0.9999.ebuild b/sys-libs/libcxx/libcxx-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..a0d07e1507f4
--- /dev/null
+++ b/sys-libs/libcxx/libcxx-20.0.0.9999.ebuild
@@ -0,0 +1,201 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~sys-libs/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{,abi} llvm/{cmake,utils/llvm-lit} cmake )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_INSTALL_MODULES=ON
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+		# this is broken with standalone builds, and also meaningless
+		-DLIBCXXABI_USE_LLVM_UNWINDER=OFF
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/sys-libs/libcxxabi/libcxxabi-18.1.8.ebuild b/sys-libs/libcxxabi/libcxxabi-18.1.8.ebuild
index b72247b1f9a9..122f3476e8da 100644
--- a/sys-libs/libcxxabi/libcxxabi-18.1.8.ebuild
+++ b/sys-libs/libcxxabi/libcxxabi-18.1.8.ebuild
@@ -12,7 +12,7 @@ HOMEPAGE="https://libcxxabi.llvm.org/"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
 SLOT="0"
-KEYWORDS="amd64 arm arm64 ~loong ~riscv ~sparc x86 ~arm64-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ~riscv sparc x86 ~arm64-macos ~x64-macos"
 IUSE="+clang +static-libs test"
 REQUIRED_USE="test? ( clang )"
 RESTRICT="!test? ( test )"
diff --git a/sys-libs/libcxxabi/libcxxabi-20.0.0.9999.ebuild b/sys-libs/libcxxabi/libcxxabi-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..903f8e866cb6
--- /dev/null
+++ b/sys-libs/libcxxabi/libcxxabi-20.0.0.9999.ebuild
@@ -0,0 +1,110 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="Low level support for a standard C++ library"
+HOMEPAGE="https://libcxxabi.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+IUSE="+clang +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+# in 15.x, cxxabi.h is moving from libcxx to libcxxabi
+RDEPEND+="
+	!<sys-libs/libcxx-15
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{abi,} llvm/cmake cmake )
+LLVM_TEST_COMPONENTS=( llvm/utils/llvm-lit )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+multilib_src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES="libcxxabi;libcxx"
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+		-DLIBCXXABI_ENABLE_SHARED=ON
+		-DLIBCXXABI_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXXABI_INCLUDE_TESTS=$(usex test)
+		-DLIBCXXABI_USE_COMPILER_RT=${use_compiler_rt}
+
+		# upstream is omitting standard search path for this
+		# probably because gcc & clang are bundling their own unwind.h
+		-DLIBCXXABI_LIBUNWIND_INCLUDES="${EPREFIX}"/usr/include
+		# this is broken with standalone builds, and also meaningless
+		-DLIBCXXABI_USE_LLVM_UNWINDER=OFF
+
+		-DLIBCXX_LIBDIR_SUFFIX=
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=OFF
+		-DLIBCXX_CXX_ABI=libcxxabi
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_HAS_GCC_S_LIB=OFF
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=OFF
+	)
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_build cxxabi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxxabi
+}
+
+multilib_src_install() {
+	DESTDIR="${D}" cmake_build install-cxxabi
+}
diff --git a/sys-libs/libomp/libomp-20.0.0.9999.ebuild b/sys-libs/libomp/libomp-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..32b91b3699c4
--- /dev/null
+++ b/sys-libs/libomp/libomp-20.0.0.9999.ebuild
@@ -0,0 +1,88 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit flag-o-matic cmake-multilib linux-info llvm.org python-single-r1
+
+DESCRIPTION="OpenMP runtime library for LLVM/clang compiler"
+HOMEPAGE="https://openmp.llvm.org"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0/${LLVM_SOABI}"
+IUSE="+debug gdb-plugin hwloc ompt test"
+REQUIRED_USE="
+	gdb-plugin? ( ${PYTHON_REQUIRED_USE} )
+"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	gdb-plugin? ( ${PYTHON_DEPS} )
+	hwloc? ( >=sys-apps/hwloc-2.5:0=[${MULTILIB_USEDEP}] )
+"
+# tests:
+# - dev-python/lit provides the test runner
+# - sys-devel/llvm provide test utils (e.g. FileCheck)
+# - sys-devel/clang provides the compiler to run tests
+DEPEND="
+	${RDEPEND}
+"
+BDEPEND="
+	dev-lang/perl
+	test? (
+		${PYTHON_DEPS}
+		$(python_gen_cond_dep '
+			dev-python/lit[${PYTHON_USEDEP}]
+		')
+		sys-devel/clang
+	)
+"
+
+LLVM_COMPONENTS=( openmp cmake llvm/include )
+llvm.org_set_globals
+
+pkg_setup() {
+	if use gdb-plugin || use test; then
+		python-single-r1_pkg_setup
+	fi
+}
+
+multilib_src_configure() {
+	# LTO causes issues in other packages building, #870127
+	filter-lto
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+
+	local libdir="$(get_libdir)"
+	local mycmakeargs=(
+		-DOPENMP_LIBDIR_SUFFIX="${libdir#lib}"
+
+		-DLIBOMP_USE_HWLOC=$(usex hwloc)
+		-DLIBOMP_OMPD_GDB_SUPPORT=$(multilib_native_usex gdb-plugin)
+		-DLIBOMP_OMPT_SUPPORT=$(usex ompt)
+
+		# do not install libgomp.so & libiomp5.so aliases
+		-DLIBOMP_INSTALL_ALIASES=OFF
+		# disable unnecessary hack copying stuff back to srcdir
+		-DLIBOMP_COPY_EXPORTS=OFF
+	)
+
+	use test && mycmakeargs+=(
+		# this project does not use standard LLVM cmake macros
+		-DOPENMP_LLVM_LIT_EXECUTABLE="${EPREFIX}/usr/bin/lit"
+		-DOPENMP_LIT_ARGS="$(get_lit_flags)"
+
+		-DOPENMP_TEST_C_COMPILER="$(type -P "${CHOST}-clang")"
+		-DOPENMP_TEST_CXX_COMPILER="$(type -P "${CHOST}-clang++")"
+	)
+	cmake_src_configure
+}
+
+multilib_src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+
+	cmake_build check-libomp
+}
diff --git a/sys-libs/llvm-libunwind/llvm-libunwind-18.1.8.ebuild b/sys-libs/llvm-libunwind/llvm-libunwind-18.1.8.ebuild
index 02d0b8fd5b4d..aaa6c07084dc 100644
--- a/sys-libs/llvm-libunwind/llvm-libunwind-18.1.8.ebuild
+++ b/sys-libs/llvm-libunwind/llvm-libunwind-18.1.8.ebuild
@@ -12,7 +12,7 @@ HOMEPAGE="https://llvm.org/docs/ExceptionHandling.html"
 
 LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
 SLOT="0"
-KEYWORDS="amd64 arm arm64 ~loong ~mips ~ppc ppc64 ~riscv ~sparc x86 ~arm64-macos ~x64-macos"
+KEYWORDS="amd64 arm arm64 ~loong ~mips ~ppc ppc64 ~riscv sparc x86 ~arm64-macos ~x64-macos"
 IUSE="+clang debug static-libs test"
 REQUIRED_USE="test? ( clang )"
 RESTRICT="!test? ( test )"
diff --git a/sys-libs/llvm-libunwind/llvm-libunwind-20.0.0.9999.ebuild b/sys-libs/llvm-libunwind/llvm-libunwind-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..e4c76c15ebc8
--- /dev/null
+++ b/sys-libs/llvm-libunwind/llvm-libunwind-20.0.0.9999.ebuild
@@ -0,0 +1,128 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="C++ runtime stack unwinder from LLVM"
+HOMEPAGE="https://llvm.org/docs/ExceptionHandling.html"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+IUSE="+clang +debug static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	!sys-libs/libunwind
+"
+DEPEND="
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libunwind libcxx llvm/cmake cmake )
+LLVM_TEST_COMPONENTS=( libcxxabi llvm/utils/llvm-lit )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+multilib_src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	local libdir=$(get_libdir)
+
+	# https://github.com/llvm/llvm-project/issues/56825
+	# also separately bug #863917
+	filter-lto
+
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	# https://github.com/gentoo/gentoo/pull/21516
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# Respect upstream build type assumptions (bug #910436) where they do:
+	# -DLIBUNWIND_ENABLE_ASSERTIONS=ON =>
+	#       -DCMAKE_BUILD_TYPE=DEBUG  => -UNDEBUG
+	#       -DCMAKE_BUILD_TYPE!=debug => -DNDEBUG
+	# -DLIBUNWIND_ENABLE_ASSERTIONS=OFF =>
+	#       -UNDEBUG
+	# See also https://github.com/llvm/llvm-project/issues/86#issuecomment-1649668826.
+	use debug || append-cppflags -DNDEBUG
+
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES="libunwind"
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLIBUNWIND_ENABLE_ASSERTIONS=$(usex debug)
+		-DLIBUNWIND_ENABLE_STATIC=$(usex static-libs)
+		-DLIBUNWIND_INCLUDE_TESTS=$(usex test)
+		-DLIBUNWIND_INSTALL_HEADERS=ON
+
+		# support non-native unwinding; given it's small enough,
+		# enable it unconditionally
+		-DLIBUNWIND_ENABLE_CROSS_UNWINDING=ON
+
+		# avoid dependency on libgcc_s if compiler-rt is used
+		-DLIBUNWIND_USE_COMPILER_RT=${use_compiler_rt}
+	)
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_ENABLE_RUNTIMES="libunwind;libcxxabi;libcxx"
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DLIBUNWIND_LIBCXX_PATH="${WORKDIR}/libcxx"
+
+			-DLIBCXXABI_LIBDIR_SUFFIX=
+			-DLIBCXXABI_ENABLE_SHARED=OFF
+			-DLIBCXXABI_ENABLE_STATIC=ON
+			-DLIBCXXABI_USE_LLVM_UNWINDER=ON
+			-DLIBCXXABI_INCLUDE_TESTS=OFF
+
+			-DLIBCXX_LIBDIR_SUFFIX=
+			-DLIBCXX_ENABLE_SHARED=OFF
+			-DLIBCXX_ENABLE_STATIC=ON
+			-DLIBCXX_CXX_ABI=libcxxabi
+			-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+			-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+			-DLIBCXX_HAS_GCC_S_LIB=OFF
+			-DLIBCXX_INCLUDE_TESTS=OFF
+			-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		)
+	fi
+
+	cmake_src_configure
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-unwind
+}
+
+multilib_src_install() {
+	DESTDIR=${D} cmake_build install-unwind
+}