diff --git a/llvm-runtimes/libunwind/Manifest b/llvm-runtimes/libunwind/Manifest
index 54ce25c1212d2..2fc5f4eff6534 100644
--- a/llvm-runtimes/libunwind/Manifest
+++ b/llvm-runtimes/libunwind/Manifest
@@ -10,5 +10,6 @@ DIST llvm-project-19.1.7.src.tar.xz 141249332 BLAKE2B 1259ed7f9aca7b35e89d818bef
 DIST llvm-project-19.1.7.src.tar.xz.sig 438 BLAKE2B 4015140f4ba77de45039bdbdfbaf6f30e75705123d067ea97175d91d7a5b6a75008df01d99ae7aa16aaa3b101f3f41e38d01f04158f95a261d617b3ede0254cd SHA512 195797b06ac80a742e0ccbc03a50dc06dd2e04377d783d5474e3e72c5a75203b60292b047929312a411d22b137a239943fba414a4d136a2be14cbff978eb6bda
 DIST llvm-project-20.1.5.src.tar.xz 147239812 BLAKE2B 992ebec16a11f32f234ba8b9f228f27939cdaeaaba474a08da2564ba3075bb10ab92a44be704666bdd77f8294321d43da40bb9245c411a86cd53cff88223a91f SHA512 3b7e657714fa9b943c75ec9eeb903018ab4713b1c3370746ba68893220729f178dabb971515741519f24e7ad0fa1dbce1345572bcf1d1fc1e5de97e4d2900a6b
 DIST llvm-project-20.1.5.src.tar.xz.sig 566 BLAKE2B c8be202b475726817893e1fe5fe2d3ab02ea1d3130ccfdf4c2c29b46e6aef79091de78e8a9aef59416ac1120bb3af6fdf47464db9b27b8fb4cb4194b0444e571 SHA512 c1bd30af5f7bfa6cac73994e9068d2791d9d27e86375fb15ad426422ad00cb43ade226c1b91ecc7daa950efae62c86300e4290d59649310f4e8fab5bdcb264fe
+DIST llvm-project-7dc7c155251c0008d5d59b84f0c9056365740f11.tar.gz 235921149 BLAKE2B 2867e313cd25fee6975da9bf65365fa51ed8780f3f8fc95983fb6e8f5b2c38c6d7f75a386b0ec2d74bafad74472973f4e4e603a5a0754465ac2b75942b8e90c6 SHA512 f8bc383ff2a1af836357150efa5728c7df3cd862f56ffaf12b5fc56ef631f1048276ff00b89fcf4d224576fa1eda9811d971886aae0855a4d29178060eb89a49
 DIST llvm-project-aaaae99663dbb220c6c27fa9cacf93fcb8f20e7c.tar.gz 235477577 BLAKE2B 46a3b7863cdfde75045dfcab95f8c9eee21f8ce80cee700284bc174adbb4038f23bba3b15635c88c2723ed0d20e6fddcf43c92b9e540c885af48e81bfa8c82aa SHA512 bf8e7f28622f91da57698220fca592105d109c38801b5e0312f5e290bca1ae32ef393179cfe912c194dbf85ece9bd6ee63b587157b0fcd6007bbaff3324e77ed
 DIST llvm-project-fcb4bda9dcfcdb64d8b069e8416c75d7a1a62e52.tar.gz 233149231 BLAKE2B 95a7a012a1e747afcf83ace3785c8ef6a3e10f6075e59eb1c5b077cc9edae244b648f341bc0ac6a45b2afc8f7ffe130a90a741a04465523f30f8322566386703 SHA512 b46f0c90a1c56750cada24183ca382b267a2d2faa0db7d77a8bdd4e94e6303e57d565cf85447b3c0e0efdd3750efef1e10e8ce6f1fe8f1ae10ee31d25ddf3fb7
diff --git a/llvm-runtimes/libunwind/libunwind-21.0.0_pre20250523.ebuild b/llvm-runtimes/libunwind/libunwind-21.0.0_pre20250523.ebuild
new file mode 100644
index 0000000000000..0264305349934
--- /dev/null
+++ b/llvm-runtimes/libunwind/libunwind-21.0.0_pre20250523.ebuild
@@ -0,0 +1,128 @@
+# Copyright 1999-2025 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="
+	llvm-core/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		llvm-core/clang:${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=( libc 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="${WORKDIR}/libcxx"
+
+			-DLIBCXXABI_LIBDIR_SUFFIX=
+			-DLIBCXXABI_ENABLE_SHARED=OFF
+			-DLIBCXXABI_ENABLE_STATIC=ON
+			-DLIBCXXABI_USE_LLVM_UNWINDER=ON
+			-DLIBCXXABI_INCLUDE_TESTS=OFF
+
+			-DLIBCXX_LIBDIR_SUFFIX=
+			-DLIBCXX_ENABLE_SHARED=OFF
+			-DLIBCXX_ENABLE_STATIC=ON
+			-DLIBCXX_CXX_ABI=libcxxabi
+			-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+			-DLIBCXX_HAS_MUSL_LIBC=$(llvm_cmake_use_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
+}