diff --git a/prepare-cross-toolchain-unix.sh b/prepare-cross-toolchain-unix.sh
new file mode 100755
index 0000000..124d442
--- /dev/null
+++ b/prepare-cross-toolchain-unix.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+#
+# Copyright (c) 2022 Martin Storsjo
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+set -e
+
+if [ $# -lt 2 ]; then
+    echo $0 src dest
+    exit 1
+fi
+SRC="$1"
+DEST="$2"
+
+: ${ARCHS:=${TOOLCHAIN_ARCHS-i686 x86_64 armv7 aarch64}}
+
+CLANG_RESOURCE_DIR="$("$SRC/bin/clang" --print-resource-dir)"
+CLANG_VERSION=$(basename "$CLANG_RESOURCE_DIR")
+
+# Copy the clang resource files (include, lib, share). The clang cross
+# build installs the main headers, but since we didn't build the runtimes
+# (compiler-rt), we're lacking the files that are installed by them. The
+# compiler-rt build primarily installs some libs, but also a few files under
+# share, and headers for some of the runtime libraries.
+#
+# Instead of trying to merge these files on top of the headers installed
+# by the clang cross build, just wipe the existing files and copy the whole
+# resource directory from the complete toolchain. As long as it's a matching
+# version of clang, the headers that were installed by it should be identical.
+#
+# Alternatively, we could copy the lib and share subdirectories, and
+# copy the individual include subdirectories that are missing.
+rm -rf $DEST/lib/clang/$CLANG_VERSION
+cp -a $CLANG_RESOURCE_DIR $DEST/lib/clang/$CLANG_VERSION
+
+# Copy all arch-specific subdirectories plus the "generic" one, as is.
+for arch in generic $ARCHS; do
+    cp -a $SRC/$arch-w64-mingw32 $DEST/$arch-w64-mingw32
+done