diff --git a/.buildkite/pipelines/experimental/launch_unsigned_builders.yml b/.buildkite/pipelines/experimental/launch_unsigned_builders.yml
index f023e19a5c940..70347077dcbce 100644
--- a/.buildkite/pipelines/experimental/launch_unsigned_builders.yml
+++ b/.buildkite/pipelines/experimental/launch_unsigned_builders.yml
@@ -1,6 +1,10 @@
 steps:
   - label: ":buildkite: Launch unsigned pipelines"
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
+      echo "--- Launch unsigned pipelines"
       buildkite-agent pipeline upload .buildkite/pipelines/experimental/misc/sanitizers.yml
     agents:
       queue: julia
diff --git a/.buildkite/pipelines/experimental/misc/sanitizers.yml b/.buildkite/pipelines/experimental/misc/sanitizers.yml
index 79af4905416fc..52e46490a2fd5 100644
--- a/.buildkite/pipelines/experimental/misc/sanitizers.yml
+++ b/.buildkite/pipelines/experimental/misc/sanitizers.yml
@@ -21,5 +21,8 @@ steps:
           version: 1.6
     timeout_in_minutes: 120
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       echo "--- Build julia-debug with ASAN"
       contrib/asan/build.sh ./tmp/test-asan -j$${JULIA_CPU_THREADS:?} debug
diff --git a/.buildkite/pipelines/main/launch_unsigned_builders.yml b/.buildkite/pipelines/main/launch_unsigned_builders.yml
index f978b0c48ed77..ffa44b95370a3 100644
--- a/.buildkite/pipelines/main/launch_unsigned_builders.yml
+++ b/.buildkite/pipelines/main/launch_unsigned_builders.yml
@@ -15,6 +15,11 @@
 steps:
   - label: ":buildkite: Launch unsigned builders"
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
+      echo "--- Launch unsigned builders"
+
       # Launch the `whitespace` builder first, because we want that builder to finish as quickly as possible.
       buildkite-agent pipeline upload .buildkite/pipelines/main/misc/whitespace.yml
 
diff --git a/.buildkite/pipelines/main/misc/doctest.yml b/.buildkite/pipelines/main/misc/doctest.yml
index e1af8d7cd839f..3471f45115544 100644
--- a/.buildkite/pipelines/main/misc/doctest.yml
+++ b/.buildkite/pipelines/main/misc/doctest.yml
@@ -18,6 +18,9 @@ steps:
             # Include `/cache/repos` so that our `git` version introspection works.
             - "/cache/repos:/cache/repos"
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       echo "--- Build Julia from source"
       make -j 6
 
diff --git a/.buildkite/pipelines/main/misc/embedding.yml b/.buildkite/pipelines/main/misc/embedding.yml
index dc5e80e85d065..575dda4132fef 100644
--- a/.buildkite/pipelines/main/misc/embedding.yml
+++ b/.buildkite/pipelines/main/misc/embedding.yml
@@ -18,12 +18,15 @@ steps:
             # Include `/cache/repos` so that our `git` version introspection works.
             - "/cache/repos:/cache/repos"
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       prefix="/tmp/prefix"
-      echo "+++ Build julia, deploy to $${prefix:?}"
+      echo "--- Build julia, deploy to $${prefix:?}"
       make -j$${JULIA_CPU_THREADS:?} JULIA_PRECOMPILE=0 prefix=$${prefix:?} install
 
       embedding_output="/tmp/embedding-test"
-      echo "+++ Run embedding tests, deploy to $${embedding_output:?}"
+      echo "--- Run embedding tests, deploy to $${embedding_output:?}"
       mkdir -p "$${embedding_output:?}"
       make -j$${JULIA_CPU_THREADS:?} -C test/embedding JULIA="$${prefix:?}/bin/julia" BIN="$${embedding_output:?}"
     timeout_in_minutes: 60
diff --git a/.buildkite/pipelines/main/misc/llvmpasses.yml b/.buildkite/pipelines/main/misc/llvmpasses.yml
index 921f39c5fb360..dd51d081d3334 100644
--- a/.buildkite/pipelines/main/misc/llvmpasses.yml
+++ b/.buildkite/pipelines/main/misc/llvmpasses.yml
@@ -16,6 +16,9 @@ steps:
             # Include `/cache/repos` so that our `git` version introspection works.
             - "/cache/repos:/cache/repos"
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       echo "--- Install in-tree LLVM dependencies"
       make -j$${JULIA_CPU_THREADS:?} -C deps install-llvm install-clang install-llvm-tools install-libuv install-utf8proc install-unwind
       echo "+++ run clangsa/analyzegc"
@@ -35,6 +38,9 @@ steps:
           workspaces:
             - "/cache/repos:/cache/repos"
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       echo "--- make release"
       make -j$${JULIA_CPU_THREADS:?} release JULIA_PRECOMPILE=0
       echo "--- make src/install-analysis-deps"
diff --git a/.buildkite/pipelines/main/misc/whitespace.yml b/.buildkite/pipelines/main/misc/whitespace.yml
index 89231b80cc48d..c0754e5e05611 100644
--- a/.buildkite/pipelines/main/misc/whitespace.yml
+++ b/.buildkite/pipelines/main/misc/whitespace.yml
@@ -19,4 +19,8 @@ steps:
       - github_commit_status:
           context: "whitespace"
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
+      echo "--- Run the whitespace check"
       make -j$${JULIA_CPU_THREADS:?} check-whitespace
diff --git a/.buildkite/pipelines/main/platforms/package_linux.yml b/.buildkite/pipelines/main/platforms/package_linux.yml
index a054390bb2c0c..49292c0f305d8 100644
--- a/.buildkite/pipelines/main/platforms/package_linux.yml
+++ b/.buildkite/pipelines/main/platforms/package_linux.yml
@@ -21,14 +21,19 @@ steps:
             - "/cache/repos:/cache/repos"
     timeout_in_minutes: ${TIMEOUT?}
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       echo "--- Print the full and short commit hashes"
       SHORT_COMMIT_LENGTH=10
-      SHORT_COMMIT=`echo $${BUILDKITE_COMMIT:?} | cut -c1-$${SHORT_COMMIT_LENGTH:?}`
+      CHECKED_OUT_COMMIT_FULL=`git rev-parse HEAD`
+      CHECKED_OUT_COMMIT_SHORT=`echo $${CHECKED_OUT_COMMIT_FULL:?} | cut -c1-$${SHORT_COMMIT_LENGTH:?}`
       JULIA_BINARYDIST_FILENAME=`make print-JULIA_BINARYDIST_FILENAME | cut -c27-`
       ARTIFACT_FILE_EXTENSION="tar.gz"
       ARTIFACT_FILENAME="$${JULIA_BINARYDIST_FILENAME:?}.$${ARTIFACT_FILE_EXTENSION:?}"
-      echo "The full commit is:                     $${BUILDKITE_COMMIT:?}"
-      echo "The short commit is:                    $${SHORT_COMMIT:?}"
+      echo "The original Buildkite commit is:       $${BUILDKITE_COMMIT:?}"
+      echo "The full checked-out commit is:         $${CHECKED_OUT_COMMIT_FULL:?}"
+      echo "The short checked-out commit is:        $${CHECKED_OUT_COMMIT_SHORT:?}"
       echo "The artifact filename will be:    $${ARTIFACT_FILENAME:?}"
 
       echo "--- Build Julia from source"
diff --git a/.buildkite/pipelines/main/platforms/tester_linux.yml b/.buildkite/pipelines/main/platforms/tester_linux.yml
index 3a71599ad6f0a..bfc87fd0e1696 100644
--- a/.buildkite/pipelines/main/platforms/tester_linux.yml
+++ b/.buildkite/pipelines/main/platforms/tester_linux.yml
@@ -24,16 +24,21 @@ steps:
       JULIA_SHELL: "/bin/bash"
     timeout_in_minutes: ${TIMEOUT?}
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       echo "--- Print the full and short commit hashes"
       SHORT_COMMIT_LENGTH=10
-      SHORT_COMMIT=`echo $${BUILDKITE_COMMIT:?} | cut -c1-$${SHORT_COMMIT_LENGTH:?}`
-      JULIA_DIR="julia-$${SHORT_COMMIT:?}"
+      CHECKED_OUT_COMMIT_FULL=`git rev-parse HEAD`
+      CHECKED_OUT_COMMIT_SHORT=`echo $${CHECKED_OUT_COMMIT_FULL:?} | cut -c1-$${SHORT_COMMIT_LENGTH:?}`
+      JULIA_DIR="julia-$${CHECKED_OUT_COMMIT_SHORT:?}"
       JULIA_BINARY="$${JULIA_DIR:?}/bin/julia"
       ARTIFACT_FILE_EXTENSION="tar.gz"
-      ARTIFACT_FILENAME="julia-$${SHORT_COMMIT:?}-linux${ARCH?}.$${ARTIFACT_FILE_EXTENSION:?}"
-      echo "The full commit is:                     $${BUILDKITE_COMMIT:?}"
-      echo "The short commit is:                    $${SHORT_COMMIT:?}"
-      echo "The artifact filename will be:    $${ARTIFACT_FILENAME:?}"
+      ARTIFACT_FILENAME="julia-$${CHECKED_OUT_COMMIT_SHORT:?}-linux${ARCH?}.$${ARTIFACT_FILE_EXTENSION:?}"
+      echo "The original Buildkite commit is:       $${BUILDKITE_COMMIT:?}"
+      echo "The full checked-out commit is:         $${CHECKED_OUT_COMMIT_FULL:?}"
+      echo "The short checked-out commit is:        $${CHECKED_OUT_COMMIT_SHORT:?}"
+      echo "The artifact filename will be:          $${ARTIFACT_FILENAME:?}"
       echo "The Julia directory name will be: $${JULIA_DIR:?}"
       echo "The Julia binary will be:         $${JULIA_BINARY:?}"
 
diff --git a/.buildkite/pipelines/scheduled/coverage/coverage_linux64.yml b/.buildkite/pipelines/scheduled/coverage/coverage_linux64.yml
index f5d93264f7aac..efe4ddb1e8aaa 100644
--- a/.buildkite/pipelines/scheduled/coverage/coverage_linux64.yml
+++ b/.buildkite/pipelines/scheduled/coverage/coverage_linux64.yml
@@ -18,6 +18,9 @@ steps:
           uid: 1000
           gid: 1000
     commands: |
+      echo "--- Checkout the merge commit (if this is a pull request build)"
+      MCSH=.buildkite/utilities/merge_commit/merge_commit.sh && test -f $${MCSH:?} && bash $${MCSH:?}
+
       echo "--- Build Julia from source"
       make -j 6
 
diff --git a/.buildkite/utilities/merge_commit/merge_commit.sh b/.buildkite/utilities/merge_commit/merge_commit.sh
new file mode 100755
index 0000000000000..29a98475baf41
--- /dev/null
+++ b/.buildkite/utilities/merge_commit/merge_commit.sh
@@ -0,0 +1,18 @@
+#!/bin/bash
+set -euo pipefail
+if [[ "${BUILDKITE_PULL_REQUEST:?}" != "false" ]]; then
+    git log -n 1
+    echo ""
+    echo "This is a pull request build."
+    echo "Pull request: ${BUILDKITE_PULL_REQUEST:?}"
+    echo "Fetching the pull request merge commit..."
+    sleep 0.01 # Make sure GitHub has enough time to create the merge commit.
+    git fetch origin +refs/pull/${BUILDKITE_PULL_REQUEST:?}/merge
+    echo "Checking out the pull request merge commit..."
+    git checkout --force FETCH_HEAD
+else
+    echo "This is not a pull request build."
+fi
+
+git log -n 1
+echo ""