diff --git a/.ci/compute-projects.sh b/.ci/compute-projects.sh
new file mode 100644
index 000000000000..32baf26b4f0a
--- /dev/null
+++ b/.ci/compute-projects.sh
@@ -0,0 +1,194 @@
+#!/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
+#
+#===----------------------------------------------------------------------===##
+
+#
+# This file contains functions to compute which projects should be built by CI
+# systems and is intended to provide common functionality applicable across
+# multiple systems during a transition period.
+#
+
+function compute-projects-to-test() {
+  isForWindows=$1
+  shift
+  projects=${@}
+  for project in ${projects}; do
+    echo "${project}"
+    case ${project} in
+    lld)
+      for p in bolt cross-project-tests; do
+        echo $p
+      done
+    ;;
+    llvm)
+      for p in bolt clang clang-tools-extra lld lldb mlir polly; do
+        echo $p
+      done
+      # Flang is not stable in Windows CI at the moment
+      if [[ $isForWindows == 0 ]]; then
+        echo flang
+      fi
+    ;;
+    clang)
+      # lldb is temporarily removed to alleviate Linux pre-commit CI waiting times
+      for p in clang-tools-extra compiler-rt cross-project-tests; do
+        echo $p
+      done
+    ;;
+    clang-tools-extra)
+      echo libc
+    ;;
+    mlir)
+      # Flang is not stable in Windows CI at the moment
+      if [[ $isForWindows == 0 ]]; then
+        echo flang
+      fi
+    ;;
+    *)
+      # Nothing to do
+    ;;
+    esac
+  done
+}
+
+function compute-runtimes-to-test() {
+  projects=${@}
+  for project in ${projects}; do
+    case ${project} in
+    clang)
+      for p in libcxx libcxxabi libunwind; do
+        echo $p
+      done
+    ;;
+    *)
+      # Nothing to do
+    ;;
+    esac
+  done
+}
+
+function add-dependencies() {
+  projects=${@}
+  for project in ${projects}; do
+    echo "${project}"
+    case ${project} in
+    bolt)
+      for p in clang lld llvm; do
+        echo $p
+      done
+    ;;
+    cross-project-tests)
+      for p in lld clang; do
+        echo $p
+      done
+    ;;
+    clang-tools-extra)
+      for p in llvm clang; do
+        echo $p
+      done
+    ;;
+    compiler-rt|libc|openmp)
+      echo clang lld
+    ;;
+    flang|lldb|libclc)
+      for p in llvm clang; do
+        echo $p
+      done
+    ;;
+    lld|mlir|polly)
+      echo llvm
+    ;;
+    *)
+      # Nothing to do
+    ;;
+    esac
+  done
+}
+
+function exclude-linux() {
+  projects=${@}
+  for project in ${projects}; do
+    case ${project} in
+    cross-project-tests) ;; # tests failing
+    openmp)              ;; # https://github.com/google/llvm-premerge-checks/issues/410
+    *)
+      echo "${project}"
+    ;;
+    esac
+  done
+}
+
+function exclude-windows() {
+  projects=${@}
+  for project in ${projects}; do
+    case ${project} in
+    cross-project-tests) ;; # tests failing
+    compiler-rt)         ;; # tests taking too long
+    openmp)              ;; # TODO: having trouble with the Perl installation
+    libc)                ;; # no Windows support
+    lldb)                ;; # custom environment requirements (https://github.com/llvm/llvm-project/pull/94208#issuecomment-2146256857)
+    bolt)                ;; # tests are not supported yet
+    *)
+      echo "${project}"
+    ;;
+    esac
+  done
+}
+
+# Prints only projects that are both present in $modified_dirs and the passed
+# list.
+function keep-modified-projects() {
+  projects=${@}
+  for project in ${projects}; do
+    if echo "$modified_dirs" | grep -q -E "^${project}$"; then
+      echo "${project}"
+    fi
+  done
+}
+
+function check-targets() {
+  # Do not use "check-all" here because if there is "check-all" plus a
+  # project specific target like "check-clang", that project's tests
+  # will be run twice.
+  projects=${@}
+  for project in ${projects}; do
+    case ${project} in
+    clang-tools-extra)
+      echo "check-clang-tools"
+    ;;
+    compiler-rt)
+      echo "check-compiler-rt"
+    ;;
+    cross-project-tests)
+      echo "check-cross-project"
+    ;;
+    libcxx)
+      echo "check-cxx"
+    ;;
+    libcxxabi)
+      echo "check-cxxabi"
+    ;;
+    libunwind)
+      echo "check-unwind"
+    ;;
+    lldb)
+      echo "check-lldb"
+    ;;
+    pstl)
+      # Currently we do not run pstl tests in CI.
+    ;;
+    libclc)
+      # Currently there is no testing for libclc.
+    ;;
+    *)
+      echo "check-${project}"
+    ;;
+    esac
+  done
+}
+
diff --git a/.ci/generate-buildkite-pipeline-premerge b/.ci/generate-buildkite-pipeline-premerge
index 190dd1e5ba5a..9d9ca3218394 100755
--- a/.ci/generate-buildkite-pipeline-premerge
+++ b/.ci/generate-buildkite-pipeline-premerge
@@ -52,184 +52,7 @@ modified_dirs=$(echo "$MODIFIED_FILES" | cut -d'/' -f1 | sort -u)
 echo "Directories modified:" >&2
 echo "$modified_dirs" >&2
 
-function compute-projects-to-test() {
-  isForWindows=$1
-  shift
-  projects=${@}
-  for project in ${projects}; do
-    echo "${project}"
-    case ${project} in
-    lld)
-      for p in bolt cross-project-tests; do
-        echo $p
-      done
-    ;;
-    llvm)
-      for p in bolt clang clang-tools-extra lld lldb mlir polly; do
-        echo $p
-      done
-      # Flang is not stable in Windows CI at the moment
-      if [[ $isForWindows == 0 ]]; then
-        echo flang
-      fi
-    ;;
-    clang)
-      # lldb is temporarily removed to alleviate Linux pre-commit CI waiting times
-      for p in clang-tools-extra compiler-rt cross-project-tests; do
-        echo $p
-      done
-    ;;
-    clang-tools-extra)
-      echo libc
-    ;;
-    mlir)
-      # Flang is not stable in Windows CI at the moment
-      if [[ $isForWindows == 0 ]]; then
-        echo flang
-      fi
-    ;;
-    *)
-      # Nothing to do
-    ;;
-    esac
-  done
-}
-
-function compute-runtimes-to-test() {
-  projects=${@}
-  for project in ${projects}; do
-    case ${project} in
-    clang)
-      for p in libcxx libcxxabi libunwind; do
-        echo $p
-      done
-    ;;
-    *)
-      # Nothing to do
-    ;;
-    esac
-  done
-}
-
-function add-dependencies() {
-  projects=${@}
-  for project in ${projects}; do
-    echo "${project}"
-    case ${project} in
-    bolt)
-      for p in clang lld llvm; do
-        echo $p
-      done
-    ;;
-    cross-project-tests)
-      for p in lld clang; do
-        echo $p
-      done
-    ;;
-    clang-tools-extra)
-      for p in llvm clang; do
-        echo $p
-      done
-    ;;
-    compiler-rt|libc|openmp)
-      echo clang lld
-    ;;
-    flang|lldb|libclc)
-      for p in llvm clang; do
-        echo $p
-      done
-    ;;
-    lld|mlir|polly)
-      echo llvm
-    ;;
-    *)
-      # Nothing to do
-    ;;
-    esac
-  done
-}
-
-function exclude-linux() {
-  projects=${@}
-  for project in ${projects}; do
-    case ${project} in
-    cross-project-tests) ;; # tests failing
-    openmp)              ;; # https://github.com/google/llvm-premerge-checks/issues/410
-    *)
-      echo "${project}"
-    ;;
-    esac
-  done
-}
-
-function exclude-windows() {
-  projects=${@}
-  for project in ${projects}; do
-    case ${project} in
-    cross-project-tests) ;; # tests failing
-    compiler-rt)         ;; # tests taking too long
-    openmp)              ;; # TODO: having trouble with the Perl installation
-    libc)                ;; # no Windows support
-    lldb)                ;; # custom environment requirements (https://github.com/llvm/llvm-project/pull/94208#issuecomment-2146256857)
-    bolt)                ;; # tests are not supported yet
-    *)
-      echo "${project}"
-    ;;
-    esac
-  done
-}
-
-# Prints only projects that are both present in $modified_dirs and the passed
-# list.
-function keep-modified-projects() {
-  projects=${@}
-  for project in ${projects}; do
-    if echo "$modified_dirs" | grep -q -E "^${project}$"; then
-      echo "${project}"
-    fi
-  done
-}
-
-function check-targets() {
-  # Do not use "check-all" here because if there is "check-all" plus a
-  # project specific target like "check-clang", that project's tests
-  # will be run twice.
-  projects=${@}
-  for project in ${projects}; do
-    case ${project} in
-    clang-tools-extra)
-      echo "check-clang-tools"
-    ;;
-    compiler-rt)
-      echo "check-compiler-rt"
-    ;;
-    cross-project-tests)
-      echo "check-cross-project"
-    ;;
-    libcxx)
-      echo "check-cxx"
-    ;;
-    libcxxabi)
-      echo "check-cxxabi"
-    ;;
-    libunwind)
-      echo "check-unwind"
-    ;;
-    lldb)
-      echo "check-lldb"
-    ;;
-    pstl)
-      # Currently we do not run pstl tests in CI.
-    ;;
-    libclc)
-      # Currently there is no testing for libclc.
-    ;;
-    *)
-      echo "check-${project}"
-    ;;
-    esac
-  done
-}
+. ./.ci/compute-projects.sh
 
 # Project specific pipelines.