diff --git a/compiler-rt/cmake/caches/AIX.cmake b/compiler-rt/cmake/caches/AIX.cmake
new file mode 100644
--- /dev/null
+++ b/compiler-rt/cmake/caches/AIX.cmake
@@ -0,0 +1,9 @@
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+set(CMAKE_BUILD_WITH_INSTALL_RPATH ON CACHE BOOL "")
+set(CMAKE_SHARED_LINKER_FLAGS
+  "-Wl,-H512 -Wl,-D0 -Wl,-T512 -Wl,-bhalt:4 -Wl,-bernotok -Wl,-bnoentry \
+   -Wl,-bexport:${AIX_LIBATOMIC_EXPORT_LIST} \
+   -Wl,bmodetype:SRE -Wl,-lc"
+  CACHE STRING "")
+
+set(COMPILER_RT_BUILD_LIBATOMIC ON CACHE BOOL "")
diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -747,4 +747,12 @@
   endforeach ()
 endif ()
 
+if (COMPILER_RT_BUILD_LIBATOMIC)
+  add_compiler_rt_runtime(clang_rt.atomic
+                          SHARED
+                          ARCHS ${BUILTIN_SUPPORTED_ARCH}
+                          SOURCES atomic.c
+                          PARENT_TARGET builtins)
+endif()
+
 add_dependencies(compiler-rt builtins)
diff --git a/compiler-rt/utils/aix-install-libatomic.sh b/compiler-rt/utils/aix-install-libatomic.sh
new file mode 100755
--- /dev/null
+++ b/compiler-rt/utils/aix-install-libatomic.sh
@@ -0,0 +1,169 @@
+#!/usr/bin/env bash
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+set -e
+
+PROGNAME="$(basename "${0}")"
+
+function error() { printf "error: %s\n" "$*"; exit 1; }
+
+function usage() {
+cat <<EOF
+Usage:
+${PROGNAME} [options]
+
+[-h|--help]                  Display this help and exit.
+
+--llvm-root <DIR>            Path to the root of the LLVM monorepo. Only the compiler-rt
+                             directory is required.
+
+--build-dir <DIR>            Path to the directory to use for building. This will
+                             contain intermediate build products.
+
+--install-dir <DIR>          Path to the directory to install the library to.
+
+--cache <PATH>               The CMake cache to use to control how the library gets built.
+EOF
+}
+
+while [[ $# -gt 0 ]]; do
+    case ${1} in
+        -h|--help)
+            usage
+            exit 0
+            ;;
+        --llvm-root)
+            llvm_root="${2}"
+            shift; shift
+            ;;
+        --build-dir)
+            build_dir="${2}"
+            shift; shift
+            ;;
+        --install-dir)
+            install_dir="${2}"
+            shift; shift
+            ;;
+        --cache)
+            cache="${2}"
+            shift; shift
+            ;;
+        *)
+            error "Unknown argument '${1}'"
+            ;;
+    esac
+done
+
+for arg in llvm_root build_dir install_dir cache; do
+    if [ -z ${!arg+x} ]; then
+        error "Missing required argument '--${arg//_/-}'"
+    elif [ "${!arg}" == "" ]; then
+        error "Argument to --${arg//_/-} must not be empty"
+    fi
+done
+
+# Allow using relative paths
+function realpath() {
+    if [[ $1 = /* ]]; then echo "$1"; else echo "$(pwd)/${1#./}"; fi
+}
+
+for arg in llvm_root build_dir install_dir cache; do
+    path="$(realpath "${!arg}")"
+    eval "${arg}=\"${path}\""
+done
+
+function step() {
+    separator="$(printf "%0.s-" $(seq 1 ${#1}))"
+    echo
+    echo "${separator}"
+    echo "${1}"
+    echo "${separator}"
+}
+
+step "Generating export list"
+exported_routines=$(cat <<EOF
+  __atomic_compare_exchange
+  __atomic_compare_exchange_1
+  __atomic_compare_exchange_2
+  __atomic_compare_exchange_4
+  __atomic_compare_exchange_8
+  __atomic_exchange
+  __atomic_exchange_1
+  __atomic_exchange_2
+  __atomic_exchange_4
+  __atomic_exchange_8
+  __atomic_fetch_add_1
+  __atomic_fetch_add_2
+  __atomic_fetch_add_4
+  __atomic_fetch_add_8
+  __atomic_fetch_and_1
+  __atomic_fetch_and_2
+  __atomic_fetch_and_4
+  __atomic_fetch_and_8
+  __atomic_fetch_or_1
+  __atomic_fetch_or_2
+  __atomic_fetch_or_4
+  __atomic_fetch_or_8
+  __atomic_fetch_sub_1
+  __atomic_fetch_sub_2
+  __atomic_fetch_sub_4
+  __atomic_fetch_sub_8
+  __atomic_fetch_xor_1
+  __atomic_fetch_xor_2
+  __atomic_fetch_xor_4
+  __atomic_fetch_xor_8
+  __atomic_is_lock_free
+  __atomic_load
+  __atomic_load_1
+  __atomic_load_2
+  __atomic_load_4
+  __atomic_load_8
+  __atomic_store
+  __atomic_store_1
+  __atomic_store_2
+  __atomic_store_4
+  __atomic_store_8
+EOF
+)
+export_list=$(realpath "${build_dir}/export_list.atomic")
+echo "${exported_routines}" > "${export_list}"
+
+cmake_path=/xl_le/gsa/tlbgsa/projects/x/xlcmpbld/bld_env/aix/cmake-3.15.7/bin/cmake
+step "Building libclang_rt.atomic-<arch>.so"
+(cd ${build_dir} && \
+  ${cmake_path} "${llvm_root}/llvm" \
+  -DAIX_LIBATOMIC_EXPORT_LIST="${export_list}" \
+  -C "${cache}" \
+  -GNinja \
+  -DLLVM_ENABLE_RUNTIMES="compiler-rt" \
+  -DLLVM_INSTALL_PREFIX="${install_dir}"
+) && \
+${cmake_path} --build "${build_dir}" --target install-builtins
+
+step "Archive built libclang_rt.atomic-<arch>.so into single libatomic.a"
+# FIXME: Clang's version is undetermined, use wildcard to match.
+atomic_32=$(find \
+            ${install_dir}/lib/clang/*/lib/aix/ \
+            -name libclang_rt.atomic-powerpc.so)
+if [[ -s "${atomic_32}" ]]
+then
+  cp "${atomic_32}" "${build_dir}/libatomic.so.1"
+  ar -X32 r "$(dirname "${atomic_32}")/libatomic.a" "${build_dir}/libatomic.so.1"
+fi
+
+atomic_64=$(find \
+            ${install_dir}/lib/clang/*/lib/aix/ \
+            -name libclang_rt.atomic-powerpc64.so)
+if [[ -s "${atomic_64}" ]]
+then
+  cp "${atomic_64}" "${build_dir}/libatomic.so.1"
+  ar -X64 r "$(dirname "${atomic_64}")/libatomic.a" "${build_dir}/libatomic.so.1"
+fi
+
+rm -f "${build_dir}/libatomic.so.1"