diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index fe65144152..bcdcc71592 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -37,7 +37,8 @@ osx-clang|osx-gcc)
 	brew update --quiet
 	# Uncomment this if you want to run perf tests:
 	# brew install gnu-time
-	brew install git-lfs gettext
+	test -z "$BREW_INSTALL_PACKAGES" ||
+	brew install $BREW_INSTALL_PACKAGES
 	brew link --force gettext
 	brew install caskroom/cask/perforce
 	;;
diff --git a/ci/lib.sh b/ci/lib.sh
index 9c6ddeb374..3f286d86a6 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -24,7 +24,7 @@ skip_branch_tip_with_tag () {
 # job if we encounter the same tree again and can provide a useful info
 # message.
 save_good_tree () {
-	echo "$(git rev-parse $TRAVIS_COMMIT^{tree}) $TRAVIS_COMMIT $TRAVIS_JOB_NUMBER $TRAVIS_JOB_ID" >>"$good_trees_file"
+	echo "$(git rev-parse $CI_COMMIT^{tree}) $CI_COMMIT $CI_JOB_NUMBER $CI_JOB_ID" >>"$good_trees_file"
 	# limit the file size
 	tail -1000 "$good_trees_file" >"$good_trees_file".tmp
 	mv "$good_trees_file".tmp "$good_trees_file"
@@ -34,7 +34,7 @@ save_good_tree () {
 # successfully before (e.g. because the branch got rebased, changing only
 # the commit messages).
 skip_good_tree () {
-	if ! good_tree_info="$(grep "^$(git rev-parse $TRAVIS_COMMIT^{tree}) " "$good_trees_file")"
+	if ! good_tree_info="$(grep "^$(git rev-parse $CI_COMMIT^{tree}) " "$good_trees_file")"
 	then
 		# Haven't seen this tree yet, or no cached good trees file yet.
 		# Continue the build job.
@@ -44,18 +44,18 @@ skip_good_tree () {
 	echo "$good_tree_info" | {
 		read tree prev_good_commit prev_good_job_number prev_good_job_id
 
-		if test "$TRAVIS_JOB_ID" = "$prev_good_job_id"
+		if test "$CI_JOB_ID" = "$prev_good_job_id"
 		then
 			cat <<-EOF
-			$(tput setaf 2)Skipping build job for commit $TRAVIS_COMMIT.$(tput sgr0)
+			$(tput setaf 2)Skipping build job for commit $CI_COMMIT.$(tput sgr0)
 			This commit has already been built and tested successfully by this build job.
 			To force a re-build delete the branch's cache and then hit 'Restart job'.
 			EOF
 		else
 			cat <<-EOF
-			$(tput setaf 2)Skipping build job for commit $TRAVIS_COMMIT.$(tput sgr0)
+			$(tput setaf 2)Skipping build job for commit $CI_COMMIT.$(tput sgr0)
 			This commit's tree has already been built and tested successfully in build job $prev_good_job_number for commit $prev_good_commit.
-			The log of that build job is available at https://travis-ci.org/$TRAVIS_REPO_SLUG/jobs/$prev_good_job_id
+			The log of that build job is available at $(url_for_job_id $prev_good_job_id)
 			To force a re-build delete the branch's cache and then hit 'Restart job'.
 			EOF
 		fi
@@ -80,11 +80,32 @@ check_unignored_build_artifacts ()
 # and installing dependencies.
 set -ex
 
-# When building a PR, TRAVIS_BRANCH refers to the *target* branch. Not what we
-# want here. We want the source branch instead.
-CI_BRANCH="${TRAVIS_PULL_REQUEST_BRANCH:-$TRAVIS_BRANCH}"
+if test true = "$TRAVIS"
+then
+	CI_TYPE=travis
+	# When building a PR, TRAVIS_BRANCH refers to the *target* branch. Not
+	# what we want here. We want the source branch instead.
+	CI_BRANCH="${TRAVIS_PULL_REQUEST_BRANCH:-$TRAVIS_BRANCH}"
+	CI_COMMIT="$TRAVIS_COMMIT"
+	CI_JOB_ID="$TRAVIS_JOB_ID"
+	CI_JOB_NUMBER="$TRAVIS_JOB_NUMBER"
+	CI_OS_NAME="$TRAVIS_OS_NAME"
+	CI_REPO_SLUG="$TRAVIS_REPO_SLUG"
+
+	cache_dir="$HOME/travis-cache"
+
+	url_for_job_id () {
+		echo "https://travis-ci.org/$CI_REPO_SLUG/jobs/$1"
+	}
+
+	BREW_INSTALL_PACKAGES="git-lfs gettext"
+	export GIT_PROVE_OPTS="--timer --jobs 3 --state=failed,slow,save"
+	export GIT_TEST_OPTS="--verbose-log -x --immediate"
+else
+	echo "Could not identify CI type" >&2
+	exit 1
+fi
 
-cache_dir="$HOME/travis-cache"
 good_trees_file="$cache_dir/good-trees"
 
 mkdir -p "$cache_dir"
@@ -94,13 +115,11 @@ skip_good_tree
 
 if test -z "$jobname"
 then
-	jobname="$TRAVIS_OS_NAME-$CC"
+	jobname="$CI_OS_NAME-$CC"
 fi
 
 export DEVELOPER=1
 export DEFAULT_TEST_TARGET=prove
-export GIT_PROVE_OPTS="--timer --jobs 3 --state=failed,slow,save"
-export GIT_TEST_OPTS="--verbose-log -x --immediate"
 export GIT_TEST_CLONE_2GB=YesPlease
 if [ "$jobname" = linux-gcc ]; then
 	export CC=gcc-8
diff --git a/ci/print-test-failures.sh b/ci/print-test-failures.sh
index 7aef39a2fd..cf321b474d 100755
--- a/ci/print-test-failures.sh
+++ b/ci/print-test-failures.sh
@@ -38,6 +38,14 @@ do
 		test_name="${TEST_EXIT%.exit}"
 		test_name="${test_name##*/}"
 		trash_dir="trash directory.$test_name"
+		case "$CI_TYPE" in
+		travis)
+			;;
+		*)
+			echo "Unhandled CI type: $CI_TYPE" >&2
+			exit 1
+			;;
+		esac
 		trash_tgz_b64="trash.$test_name.base64"
 		if [ -d "$trash_dir" ]
 		then
diff --git a/ci/test-documentation.sh b/ci/test-documentation.sh
index d3cdbac73f..7d0beb2832 100755
--- a/ci/test-documentation.sh
+++ b/ci/test-documentation.sh
@@ -5,6 +5,7 @@
 
 . ${0%/*}/lib.sh
 
+test -n "$ALREADY_HAVE_ASCIIDOCTOR" ||
 gem install asciidoctor
 
 make check-builtins