diff --git a/README.md b/README.md
index 30c07d8..2207dca 100644
--- a/README.md
+++ b/README.md
@@ -37,6 +37,11 @@ A script for use as a git mergetool; runs Emacs ediff as the mergetool.
 Lists all the authors of commits in a git repository.
 [Documentation](git-authors) at top of file.
 
+### git-clone-or-pull
+
+Either clones a repository, or pulls it if it is already cloned.
+[Documentation](git-clone-or-pull) at top of file.
+
 ### git-clone-related
 
 Clones a repository related to the one where this script is called, trying
diff --git a/git-clone-or-pull b/git-clone-or-pull
new file mode 100755
index 0000000..8d6c2c7
--- /dev/null
+++ b/git-clone-or-pull
@@ -0,0 +1,60 @@
+#!/bin/sh
+
+# git-clone-or-pull:  clone a GitHub repository, or pull it if already cloned.
+#
+# Usage: git-clone-or-pull ORG REPO_NAME [DESTINATION_PARENT] [GIT_CLONE_ARGS...]
+#   ORG is the GitHub organization
+#   REPO_NAME is the repository name (without the organization)
+#   DESTINATION_PARENT is the directory that contains the clone directory.  It
+#     defaults to the current directory.
+#   GIT_CLONE_ARGS is extra arguments to git clone.  It defaults to
+#     "-q --single-branch --depth 1" (without the quotes).
+#     It is not used if the destination already exists.
+
+SCRIPT_NAME="$(basename "$0")"
+
+if [ "$#" -lt 2 ]; then
+  echo "Usage: ${SCRIPT_NAME} ORG REPO_NAME [DESTINATION_PARENT] [GIT_CLONE_ARGS...]" >&2
+  exit 1
+fi
+
+beginswith() { case $2 in "$1"*) true ;; *) false ;; esac }
+
+ORG=$1
+shift
+REPO_NAME=$1
+shift
+DESTINATION_PARENT=.
+if [ "$#" -ne 0 ]; then
+  if ! beginswith "-" "$1"; then
+    # Does not start with "-" and therefore isn't a command-line argument.
+    DESTINATION_PARENT=$1
+    shift
+    if [ ! -d "${DESTINATION_PARENT}" ]; then
+      mkdir -p "${DESTINATION_PARENT}"
+    fi
+  fi
+fi
+if [ "$#" -eq 0 ]; then
+  # Default command-line arguments.
+  set -- -q --single-branch --depth 1
+fi
+
+REPO_URL="https://github.com/${ORG}/${REPO_NAME}.git"
+DESTINATION="${DESTINATION_PARENT:?}/${REPO_NAME}"
+
+# Try twice in case of network lossage.  60 seconds is not enough to clone a branch of the JDK.
+if test -d "${DESTINATION}"; then
+  (cd "${DESTINATION}" && (timeout 180 git pull -q || (sleep 1m && (timeout 180 git pull || true))))
+else
+  if ! timeout 180 git clone "$@" "${REPO_URL}" "${DESTINATION}"; then
+    rm -rf "${DESTINATION}"
+    sleep 180
+    if ! timeout 180 git clone "$@" "${REPO_URL}" "${DESTINATION}"; then
+      echo "Failed to clone ${REPO_URL}"
+      exit 1
+    fi
+  fi
+fi
+
+echo "${SCRIPT_NAME}: ${REPO_NAME} is at $(cd "${DESTINATION}" && git rev-parse HEAD)"
diff --git a/git-clone-related b/git-clone-related
index 2b12450..5b24970 100755
--- a/git-clone-related
+++ b/git-clone-related
@@ -175,15 +175,16 @@ else
   fi
   echo "${SCRIPT_NAME}: About to run: git clone -q -b ${REPO_BRANCH} $* ${REPO_URL} ${DESTINATION}"
   # Try twice in case of network lossage.  60 seconds is not enough to clone a branch of the JDK.
-  timeout 180 git clone -q -b "${REPO_BRANCH}" "$@" "${REPO_URL}" "${DESTINATION}" \
-    || { echo "Retrying 'git clone ... ${REPO_URL} ${DESTINATION}' after timeout" \
-      && rm -rf "${DESTINATION}" \
-      && sleep 180 \
-      && { timeout 180 git clone -q -b "${REPO_BRANCH}" "$@" "${REPO_URL}" "${DESTINATION}" \
-        || {
-          echo "${SCRIPT_NAME}: failed: git clone -q -b ${REPO_BRANCH}" "$@" "${REPO_URL} ${DESTINATION}"
-          exit 2
-        }; }; }
+  if ! timeout 180 git clone -q -b "${REPO_BRANCH}" "$@" "${REPO_URL}" "${DESTINATION}"; then
+    echo "Retrying 'git clone ... ${REPO_URL} ${DESTINATION}'"
+    rm -rf "${DESTINATION}"
+    sleep 180
+    if ! timeout 180 git clone -b "${REPO_BRANCH}" "$@" "${REPO_URL}" "${DESTINATION}"; then
+      echo "${SCRIPT_NAME}: failed: git clone -b ${REPO_BRANCH}" "$@" "${REPO_URL} ${DESTINATION}"
+      exit 2
+    fi
+  fi
+
 fi
 
 echo "${SCRIPT_NAME}: ${DESTINATION} is at $(cd "${DESTINATION}" && git rev-parse HEAD)"
diff --git a/tests/git-clone-related-test/test-git-clone-related.sh b/tests/git-clone-related-test/test-git-clone-related.sh
index 3974014..39f4405 100755
--- a/tests/git-clone-related-test/test-git-clone-related.sh
+++ b/tests/git-clone-related-test/test-git-clone-related.sh
@@ -15,6 +15,9 @@ ARGS=$3
 GOAL_REPO=$4
 GOAL_BRANCH=$5
 
+DEBUG=
+# DEBUG=--debug
+
 set -o errexit -o nounset
 # set -o pipefail
 
@@ -38,10 +41,10 @@ unset TRAVIS
 unset CIRCLE_COMPARE_URL
 unset GITHUB_HEAD_REF
 
-echo "$0: About to run: (cd $startdir && ${GIT_SCRIPTS}/git-clone-related $ARGS $resultdir)"
-# shellcheck disable=SC2086  # $ARGS should not be quoted
-(cd "$startdir" && "${GIT_SCRIPTS}"/git-clone-related $ARGS "$resultdir")
-echo "$0: Done: (cd $startdir && ${GIT_SCRIPTS}/git-clone-related $ARGS $resultdir)"
+echo "$0: About to run: (cd $startdir && ${GIT_SCRIPTS}/git-clone-related $DEBUG $ARGS $resultdir)"
+# shellcheck disable=SC2086  # $DEBUG and $ARGS should not be quoted
+(cd "$startdir" && "${GIT_SCRIPTS}"/git-clone-related $DEBUG $ARGS "$resultdir")
+echo "$0: Done: (cd $startdir && ${GIT_SCRIPTS}/git-clone-related $DEBUG $ARGS $resultdir)"
 
 clonedrepo=$(git -C "$resultdir" config --get remote.origin.url)
 # git 2.22 and later has `git branch --show-current`; CircleCI doesn't have that version yet.