diff --git a/.github/scripts/lanes.mjs b/.github/scripts/lanes.mjs
index 6820c5052aba9..8c2a308268b28 100644
--- a/.github/scripts/lanes.mjs
+++ b/.github/scripts/lanes.mjs
@@ -156,7 +156,7 @@ const platforms = [
       // ASAN is x64 only: LLVM ships no Windows ARM64 ASAN runtime. The sanitizer runtime (import lib, /MT runtime
       // thunk, DLL) comes from the compiler-rt-windows-* release tag.
       amd64: ["release", "lto", "debug", "asan"],
-      // No arm64 lto: LLVM 21's CodeView emitter has no register mapping for ARM64 NEON quad-register tuples
+      // No arm64 lto: LLVM's CodeView emitter (still true of 23.1) has no register mapping for ARM64 NEON quad-register tuples
       // ("LLVM ERROR: unknown codeview register Q22_Q23_Q24_Q25") and the LTO codegen allocates values into them.
       arm64: ["release", "debug"],
     },
diff --git a/.github/workflows/mirror-llvm-debs.yml b/.github/workflows/mirror-llvm-debs.yml
index 15f236a7eee95..73dad65464d1a 100644
--- a/.github/workflows/mirror-llvm-debs.yml
+++ b/.github/workflows/mirror-llvm-debs.yml
@@ -9,7 +9,7 @@ on:
       llvm_version:
         description: 'LLVM major version to mirror'
         type: string
-        default: '21'
+        default: '23'
 
 permissions:
   contents: write
diff --git a/Dockerfile b/Dockerfile
index 693a114c9a794..87d4f9950bad5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,7 +2,7 @@ ARG MARCH_FLAG=""
 ARG WEBKIT_RELEASE_TYPE=Release
 ARG LTO_FLAG="-flto=thin -fno-split-lto-unit -fwhole-program-vtables -fforce-emit-vtables "
 ARG RELEASE_FLAGS="-O3 -DNDEBUG=1"
-ARG LLVM_VERSION="21"
+ARG LLVM_VERSION="23"
 # The -lto variants append -g1 (line tables only) after this, see $G below; every other variant keeps full -g.
 ARG DEFAULT_CFLAGS="-mno-omit-leaf-frame-pointer -g -fno-omit-frame-pointer -ffunction-sections -fdata-sections -faddrsig -fno-unwind-tables -fno-asynchronous-unwind-tables -DU_STATIC_IMPLEMENTATION=1 "
 ARG ENABLE_SANITIZERS=""
@@ -105,8 +105,8 @@ RUN update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-13 130 \
 # GitHub release so the image doesn't depend on apt.llvm.org at build time.
 # Ubuntu-archive dependencies still come from apt. Regenerate via
 # scripts/mirror-llvm-debs.sh (or the mirror-llvm-debs workflow).
-ARG LLVM_DEBS_SHA256_amd64=759ea9d6d50de9b6062cf40161a24a3a9d70aaf11aa1a544074d126590eb55f7
-ARG LLVM_DEBS_SHA256_arm64=4d4923baa663cb2e1be67e8e7097220604489b0da8b7a4ab5911ac2baf1e0ba6
+ARG LLVM_DEBS_SHA256_amd64=6a6abdf5237c8905c44423cb7ee25e687a2c9715b5133258f6dad65ff6e6bc53
+ARG LLVM_DEBS_SHA256_arm64=57e82d805bc3214fb7170715a01a5a207112fabbdef564c8153d89b10f9ff853
 RUN curl -fsSL --retry 5 --retry-connrefused \
         "https://github.com/oven-sh/WebKit/releases/download/llvm-${LLVM_VERSION}-debs/llvm-${LLVM_VERSION}-focal-amd64.tar.gz" \
         -o /tmp/llvm.tar.gz \
diff --git a/Dockerfile.android b/Dockerfile.android
index 1f770659264b8..fd9171870109c 100644
--- a/Dockerfile.android
+++ b/Dockerfile.android
@@ -1,8 +1,8 @@
 ARG MARCH_FLAG="-march=armv8-a+crc -mtune=cortex-a78"
 ARG WEBKIT_RELEASE_TYPE=Release
 ARG LTO_FLAG=""
-ARG LLVM_VERSION="21"
-ARG LLVM_DEBS_SHA256="4a79b0eae89af72b082997d361198f16aaefce3fa8ad3c56c8e97311ff31dd5f"
+ARG LLVM_VERSION="23"
+ARG LLVM_DEBS_SHA256="993eba8b8ca23ea4d6074643d52ff9397b411e6ac5af6b7b2ca09dca2b351011"
 ARG NDK_VERSION="r27c"
 ARG NDK_SHA256="59c2f6dc96743b5daf5d1626684640b20a6bd2b1d85b13156b90333741bad5cc"
 ARG ANDROID_API="28"
@@ -27,7 +27,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 # Host clang (same version Bun uses) — we cross-compile via --target/--sysroot,
 # not via the NDK's bundled clang. apt.llvm.org installs version-suffixed names
-# only (ld.lld-21, not ld.lld), so add unversioned links for -fuse-ld=lld.
+# only (ld.lld-23, not ld.lld), so add unversioned links for -fuse-ld=lld.
 # The debs are mirrored from apt.llvm.org to a GitHub release (see
 # scripts/mirror-llvm-debs.sh) so the build doesn't depend on apt.llvm.org.
 ADD --checksum=sha256:${LLVM_DEBS_SHA256} \
diff --git a/Dockerfile.freebsd b/Dockerfile.freebsd
index 5898c557c1700..2aa7769bba214 100644
--- a/Dockerfile.freebsd
+++ b/Dockerfile.freebsd
@@ -1,8 +1,8 @@
 ARG MARCH_FLAG="-march=nehalem"
 ARG WEBKIT_RELEASE_TYPE=Release
 ARG LTO_FLAG=""
-ARG LLVM_VERSION="21"
-ARG LLVM_DEBS_SHA256="4a79b0eae89af72b082997d361198f16aaefce3fa8ad3c56c8e97311ff31dd5f"
+ARG LLVM_VERSION="23"
+ARG LLVM_DEBS_SHA256="993eba8b8ca23ea4d6074643d52ff9397b411e6ac5af6b7b2ca09dca2b351011"
 ARG FREEBSD_VERSION="14.3"
 ARG FREEBSD_ARCH="x86_64"
 ARG DEFAULT_CFLAGS="-mno-omit-leaf-frame-pointer -fno-omit-frame-pointer -ffunction-sections -fdata-sections -faddrsig -fno-unwind-tables -fno-asynchronous-unwind-tables -DU_STATIC_IMPLEMENTATION=1 "
@@ -56,7 +56,8 @@ RUN set -eux; \
       *) echo "unsupported FREEBSD_ARCH ${FREEBSD_ARCH}" >&2; exit 1 ;; \
     esac; \
     mkdir -p /opt/freebsd-sysroot; \
-    wget -q "https://download.freebsd.org/releases/${FBSD_DL_ARCH}/${FREEBSD_VERSION}-RELEASE/base.txz" -O /tmp/base.txz; \
+    wget -q "https://download.freebsd.org/releases/${FBSD_DL_ARCH}/${FREEBSD_VERSION}-RELEASE/base.txz" -O /tmp/base.txz || \
+      wget -q "https://archive.freebsd.org/old-releases/${FBSD_DL_ARCH}/${FREEBSD_VERSION}-RELEASE/base.txz" -O /tmp/base.txz; \
     tar -C /opt/freebsd-sysroot -xJf /tmp/base.txz ./usr/include ./usr/lib ./lib; \
     rm /tmp/base.txz
 ENV FREEBSD_SYSROOT=/opt/freebsd-sysroot
diff --git a/Dockerfile.macos b/Dockerfile.macos
index 3c8e0c92b7fc5..b8285cb3744de 100644
--- a/Dockerfile.macos
+++ b/Dockerfile.macos
@@ -28,8 +28,8 @@ ARG BUN_DOWNLOAD_URL="https://pub-5e11e972747a44bf9aaf9394f185a982.r2.dev/releas
 ARG WEBKIT_RELEASE_TYPE=Release
 ARG LTO_FLAG=""
 ARG MARCH_FLAG="-mcpu=apple-m1"
-ARG LLVM_VERSION="21"
-ARG LLVM_DEBS_SHA256="4a79b0eae89af72b082997d361198f16aaefce3fa8ad3c56c8e97311ff31dd5f"
+ARG LLVM_VERSION="23"
+ARG LLVM_DEBS_SHA256="993eba8b8ca23ea4d6074643d52ff9397b411e6ac5af6b7b2ca09dca2b351011"
 ARG BOOTSTRAP_CMDS_TAG="bootstrap_cmds-138"
 # What every variant is compiled with. Cross-only additions live in the build stage.
 ARG DEFAULT_CFLAGS="-fno-exceptions -fvisibility=hidden -fvisibility-inlines-hidden -O3 -g -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -faddrsig "
@@ -46,8 +46,8 @@ ARG ENABLE_MALLOC_HEAP_BREAKDOWN="OFF"
 ARG ENABLE_SANITIZERS=""
 ARG USE_MIMALLOC="OFF"
 ARG USE_EXTERNAL_MIMALLOC="OFF"
-ARG COMPILER_RT_DARWIN_TAG="compiler-rt-darwin-21.1.8"
-ARG COMPILER_RT_DARWIN_SHA256="f9bab8191d63873682ec69492d06cfdf0807a7335c4e9b188ef013b3cc3c9dbc"
+ARG COMPILER_RT_DARWIN_TAG="compiler-rt-darwin-23.1.1"
+ARG COMPILER_RT_DARWIN_SHA256="35241a2d4cff6119b78279ace69cf89c9a190bd5ec7d2baa8d9d7f2a45d9957b"
 
 FROM ubuntu:24.04 AS base
 SHELL ["/bin/bash", "-o", "pipefail", "-c"]
@@ -119,7 +119,7 @@ ENV MACOS_SDK=/opt/MacOSX${MACOS_SDK_VERSION}.sdk
 # in Dockerfile). Installed into clang's resource dir where the darwin
 # driver looks for libclang_rt.*_osx*.
 ADD --checksum=sha256:${COMPILER_RT_DARWIN_SHA256} \
-    https://github.com/oven-sh/WebKit/releases/download/${COMPILER_RT_DARWIN_TAG}/compiler-rt-darwin-21.1.8-arm64.tar.gz /compiler-rt-darwin.tar.gz
+    https://github.com/oven-sh/WebKit/releases/download/${COMPILER_RT_DARWIN_TAG}/compiler-rt-darwin-23.1.1-arm64.tar.gz /compiler-rt-darwin.tar.gz
 RUN tar -xzf /compiler-rt-darwin.tar.gz -C /usr/lib/llvm-${LLVM_VERSION}/lib/clang/${LLVM_VERSION}/lib/ && \
     rm /compiler-rt-darwin.tar.gz && \
     test -f /usr/lib/llvm-${LLVM_VERSION}/lib/clang/${LLVM_VERSION}/lib/darwin/libclang_rt.asan_osx_dynamic.dylib
diff --git a/Dockerfile.musl b/Dockerfile.musl
index 2b72e53fa8124..ebc80602503e8 100644
--- a/Dockerfile.musl
+++ b/Dockerfile.musl
@@ -13,16 +13,23 @@ ARG LINUX_ARCH="x86_64"
 # Without that, it is built here like any other stage. Lane settings belong in `lane` below.
 FROM alpine:3.23 as base
 
+# LLVM 23 is in Alpine edge only. `@edge` is a tagged repository: apk takes a package from it only when the package is
+# asked for with that tag, or when a tagged package needs something 3.23 does not have. So musl, libstdc++ and gcc stay
+# 3.23's, here and in the aarch64 sysroot below (which copies /etc/apk/repositories). The one thing that does follow
+# clang from edge is libgcc-static (libgcc.a and the crt files of this container's architecture; 3.23 has no such
+# package): the sysroot step checks that it is still the GCC version of the sysroot's.
+# Edge is a rolling repository: a rebuild of this stage takes the 23.x that is there on that day.
+RUN echo "@edge https://dl-cdn.alpinelinux.org/alpine/edge/main" >> /etc/apk/repositories
 RUN apk update
-RUN apk add --no-cache cmake make clang21 clang21-static clang21-dev llvm21-dev llvm21-static musl-dev git lld libgcc gcc g++ libstdc++ build-base lld-dev llvm21-libs libc-dev xz zlib zlib-dev libxml2 libxml2-dev
+RUN apk add --no-cache cmake make clang23@edge llvm23@edge lld23@edge musl-dev git libgcc gcc g++ libstdc++ build-base libc-dev xz zlib zlib-dev libxml2 libxml2-dev
 # What the ICU and WebKit stages need on top of that.
 RUN apk add --no-cache cpio curl tar nodejs patch file gnupg ninja ruby ruby-getoptlong unzip rsync perl python3 openssl-dev openssl linux-headers
 
-ENV CXX=clang++-21
-ENV CC=clang-21
-ENV LDFLAGS='-L/usr/include -L/usr/include/llvm21'
-ENV CXXFLAGS="-I/usr/include -I/usr/include/llvm21"
-ENV PATH="/usr/bin:/usr/local/bin:/zig/bin:/usr/lib/llvm21/bin:$PATH"
+ENV CXX=clang++-23
+ENV CC=clang-23
+ENV LDFLAGS='-L/usr/include -L/usr/include/llvm23'
+ENV CXXFLAGS="-I/usr/include -I/usr/include/llvm23"
+ENV PATH="/usr/bin:/usr/local/bin:/zig/bin:/usr/lib/llvm23/bin:$PATH"
 ENV WEBKIT_OUT_DIR=/webkitbuild
 RUN mkdir -p /output/lib /output/include /output/include/JavaScriptCore /output/include/wtf /output/include/bmalloc /output/include/unicode
 
@@ -55,12 +62,13 @@ RUN curl -fsSL "https://github.com/facebook/zstd/releases/download/v${ZSTD_VERSI
 # <sysroot>/usr/include/fortify. This container has them as a dependency of clang; a sysroot has no clang, and without
 # them the define does nothing (musl has no fortify of its own) and the aarch64 lanes lose the checks the x86_64 ones have.
 #
-# The clang configuration file: Alpine gives clang its default flags in /etc/clang21/<triple>.cfg, which clang reads for
+# The clang configuration file: Alpine gives clang its default flags in /etc/clang23/<triple>.cfg, which clang reads for
 # the triple it compiles for. The clang package installs the container's own (-fstack-clash-protection); the aarch64
 # package installs the same file under the aarch64 triple, and here nothing does, so it is copied: the aarch64 lanes
 # then get every default the x86_64 ones get, whatever Alpine puts there.
 #
-# The musl and the fortify-headers an artifact is built against must be the container's own: checked here.
+# The musl and the fortify-headers an artifact is built against must be the container's own, and its libgcc and crt
+# files the same GCC version as the container's: checked here.
 # ───────────────────────────────────────────────────────────────────────────
 ENV SYSROOT_AARCH64=/opt/sysroot-aarch64
 RUN set -eu; \
@@ -78,9 +86,14 @@ RUN set -eu; \
     echo "fortify-headers: container $container, aarch64 sysroot $sysroot"; \
     [ -n "$container" ] || { echo "error: this container has no fortify-headers" >&2; exit 1; }; \
     [ "$container" = "$sysroot" ] || { echo "error: the aarch64 sysroot's fortify-headers is not the container's" >&2; exit 1; }; \
+    container=$(env -u CFLAGS -u CXXFLAGS -u LDFLAGS ${CC} -v 2>&1 | sed -n 's|^Selected GCC installation: .*/||p'); \
+    sysroot=$(env -u CFLAGS -u CXXFLAGS -u LDFLAGS ${CC} --target=aarch64-alpine-linux-musl --sysroot="$SYSROOT_AARCH64" -v 2>&1 | sed -n 's|^Selected GCC installation: .*/||p'); \
+    echo "GCC installation clang selects: container $container, aarch64 sysroot $sysroot"; \
+    [ -n "$container" ] || { echo "error: clang selects no GCC installation in this container" >&2; exit 1; }; \
+    [ "$container" = "$sysroot" ] || { echo "error: the aarch64 sysroot's GCC is not the version of the container's (libgcc-static from edge has moved on)" >&2; exit 1; }; \
     test -f "$SYSROOT_AARCH64/usr/include/fortify/string.h"; \
-    test -s /etc/clang21/x86_64-alpine-linux-musl.cfg; \
-    cp /etc/clang21/x86_64-alpine-linux-musl.cfg /etc/clang21/aarch64-alpine-linux-musl.cfg; \
+    test -s /etc/clang23/x86_64-alpine-linux-musl.cfg; \
+    cp /etc/clang23/x86_64-alpine-linux-musl.cfg /etc/clang23/aarch64-alpine-linux-musl.cfg; \
     test -f "$SYSROOT_AARCH64/usr/lib/libc.so"; \
     test -f "$SYSROOT_AARCH64/usr/lib/libstdc++.a"; \
     ls -d "$SYSROOT_AARCH64"/usr/lib/gcc/aarch64-alpine-linux-musl/*/crtbegin.o
diff --git a/Dockerfile.windows b/Dockerfile.windows
index a3968366a0406..2d2df0b75962a 100644
--- a/Dockerfile.windows
+++ b/Dockerfile.windows
@@ -33,8 +33,8 @@ ARG ICU_MARCH_FLAG="-march=nehalem"
 ARG ENABLE_SANITIZERS=""
 ARG USE_MIMALLOC="OFF"
 ARG USE_EXTERNAL_MIMALLOC="OFF"
-ARG LLVM_VERSION="21"
-ARG LLVM_DEBS_SHA256="4a79b0eae89af72b082997d361198f16aaefce3fa8ad3c56c8e97311ff31dd5f"
+ARG LLVM_VERSION="23"
+ARG LLVM_DEBS_SHA256="993eba8b8ca23ea4d6074643d52ff9397b411e6ac5af6b7b2ca09dca2b351011"
 ARG XWIN_VERSION="0.9.0"
 ARG XWIN_SHA256="31e1033f30608ba6b821d17f1461042bd54c23424813c9b4e9ae15b6d32fa4cd"
 # Pinned MSVC CRT + Windows SDK versions. Bump deliberately; the manifest on
@@ -161,10 +161,10 @@ RUN set -e; \
 # 2.0 with LLVM exceptions; redistribution is permitted.
 # OptionsMSVC.cmake's find_library(CLANG_BUILTINS_LIBRARY) searches
 # WebKitLibraries/windows, which is symlinked to /winsdk in the build stage.
-ADD --checksum=sha256:9cff03d2c5218693b1f91efc0074957c710eeddd932d57a681c8f558b81fbe8e \
-    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-21.1.8/clang_rt.builtins-x86_64.lib /winsdk/clang_rt.builtins-x86_64.lib
-ADD --checksum=sha256:b1bfec6276dde6166aa038de10c378ec17996779786fe1747c40b833cb826e16 \
-    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-21.1.8/clang_rt.builtins-aarch64.lib /winsdk/clang_rt.builtins-aarch64.lib
+ADD --checksum=sha256:a4bd318f1337b876bfe97ac8a512708b586ad1a881d92e574233e19f8f25879c \
+    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-23.1.1/clang_rt.builtins-x86_64.lib /winsdk/clang_rt.builtins-x86_64.lib
+ADD --checksum=sha256:b4105785d8b0f39bbcd958fd2fbafeb11b5441a0b85fe55b5cf51a48a520ca38 \
+    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-23.1.1/clang_rt.builtins-aarch64.lib /winsdk/clang_rt.builtins-aarch64.lib
 
 # Windows ASAN/UBSan runtime for the -asan variant, mirrored from the same
 # LLVM release as the builtins above (x64 only: LLVM ships no Windows ARM64
@@ -175,14 +175,14 @@ ADD --checksum=sha256:b1bfec6276dde6166aa038de10c378ec17996779786fe1747c40b833cb
 # UBSan handlers, so -fsanitize=address,undefined needs no separate
 # ubsan_standalone libraries. A Linux LLVM install doesn't ship any of these;
 # WebKitCompilerFlags.cmake locates them via CLANG_LIB_PATH (set below).
-ADD --checksum=sha256:3dff47943143ab2c1a786a7c90c88f897bfa34e8b5a4c9382eadf8373fd19ec0 \
-    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-21.1.8/clang_rt.asan_dynamic-x86_64.lib /winsdk/clang_rt.asan_dynamic-x86_64.lib
-ADD --checksum=sha256:d4a0398ed7d2e1361674fbb2cfceec4df502052cfe17b51718b061e9fe523719 \
-    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-21.1.8/clang_rt.asan_static_runtime_thunk-x86_64.lib /winsdk/clang_rt.asan_static_runtime_thunk-x86_64.lib
-ADD --checksum=sha256:b3c1d6c988792651cc0b0b61b4114cbe513a5e2f6beb067fd54a96b98be9b328 \
-    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-21.1.8/clang_rt.asan_dynamic_runtime_thunk-x86_64.lib /winsdk/clang_rt.asan_dynamic_runtime_thunk-x86_64.lib
-ADD --checksum=sha256:14025e779d3c67c53027312d7542aea8f814e5237e59f41cfc6165666189f886 \
-    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-21.1.8/clang_rt.asan_dynamic-x86_64.dll /winsdk/clang_rt.asan_dynamic-x86_64.dll
+ADD --checksum=sha256:d7b1528432b69fe4fc924b29bf17729ec1eac1e2a9f6ff3384059ae71743d00c \
+    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-23.1.1/clang_rt.asan_dynamic-x86_64.lib /winsdk/clang_rt.asan_dynamic-x86_64.lib
+ADD --checksum=sha256:2687c8aa22884f4defb160ad8368e715390c72f6b6f1f7f5d632a0cf37ab879d \
+    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-23.1.1/clang_rt.asan_static_runtime_thunk-x86_64.lib /winsdk/clang_rt.asan_static_runtime_thunk-x86_64.lib
+ADD --checksum=sha256:bcd9f8c2c8041ba8e4ad0f3cb642bbf9a173d757fc864ffcc097da8661047379 \
+    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-23.1.1/clang_rt.asan_dynamic_runtime_thunk-x86_64.lib /winsdk/clang_rt.asan_dynamic_runtime_thunk-x86_64.lib
+ADD --checksum=sha256:4fc14438122d1c397698099fcb0e1bdbca4af1a2524f3426c6815dcfaa639369 \
+    https://github.com/oven-sh/WebKit/releases/download/compiler-rt-windows-23.1.1/clang_rt.asan_dynamic-x86_64.dll /winsdk/clang_rt.asan_dynamic-x86_64.dll
 
 # Sanity check: compile + link a PE executable for both arches.
 RUN for pair in "x86_64 x64" "aarch64 arm64"; do \
diff --git a/JSTests/stress/ftl-osr-exit-materialize-phantom-array-with-live-butterfly.js b/JSTests/stress/ftl-osr-exit-materialize-phantom-array-with-live-butterfly.js
index aceb48a33f535..c5b2e0618873d 100644
--- a/JSTests/stress/ftl-osr-exit-materialize-phantom-array-with-live-butterfly.js
+++ b/JSTests/stress/ftl-osr-exit-materialize-phantom-array-with-live-butterfly.js
@@ -2,6 +2,10 @@
 //@ runDefault("--forceEagerCompilation=1")
 
 let total = 0;
+// Near the stack limit the call to check() itself overflows, so `total` stops advancing while every level still runs
+// its 1024 * 16 retries: how many such levels there are depends on native frame sizes, and each one multiplies the run
+// time by ~16000. The catch block runs either way, so it bounds the test too.
+let caught = 0;
 function check(v3) {
     if (++total > 10000)
         quit(0);
@@ -15,6 +19,8 @@ function main() {
             try {
                 check(v3);
             } catch {
+                if (++caught > 50000)
+                    quit(0);
                 const x = (() => {
                     const a = new Array(8);
                     a[0] = {}, a[1] = {}, a[2] = {}, a[3] = {}, a[0] = {}, a[5] = {}, a[6] = {}, a[7] = {};
diff --git a/scripts/mirror-llvm-debs.sh b/scripts/mirror-llvm-debs.sh
index 6be3e766f5ec3..d5c41dc8fc828 100755
--- a/scripts/mirror-llvm-debs.sh
+++ b/scripts/mirror-llvm-debs.sh
@@ -16,7 +16,7 @@
 set -euo pipefail
 
 REPO="${REPO:-oven-sh/WebKit}"
-LLVM_VERSION="${LLVM_VERSION:-21}"
+LLVM_VERSION="${LLVM_VERSION:-23}"
 TAG="${TAG:-llvm-${LLVM_VERSION}-debs}"
 OUT="${OUT:-/tmp/llvm-debs}"
 V="$LLVM_VERSION"