diff --git a/ci/lib-ci-type.sh b/ci/lib-ci-type.sh
index 6f01fd9e5d9..09acab7aaec 100644
--- a/ci/lib-ci-type.sh
+++ b/ci/lib-ci-type.sh
@@ -3,7 +3,4 @@
 if test "$GITHUB_ACTIONS" = "true"
 then
 	CI_TYPE=github-actions
-else
-	echo "Could not identify CI type" >&2
-	exit 1
 fi
diff --git a/ci/lib-online_cpus.sh b/ci/lib-online_cpus.sh
new file mode 100644
index 00000000000..7cf0cd042fa
--- /dev/null
+++ b/ci/lib-online_cpus.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+# TODO: Ideally we'd compile t/helper/test-online-cpus.c early, but
+# that currently presents a chicken & egg problem. We need this before
+# we build (much of) anything.
+online_cpus() {
+	NPROC=
+
+	if command -v nproc >/dev/null
+	then
+		# GNU coreutils
+		NPROC=$(nproc)
+	elif command -v sysctl >/dev/null
+	then
+		# BSD & Mac OS X
+		NPROC=$(sysctl -n hw.ncpu)
+	elif test -n "$NUMBER_OF_PROCESSORS"
+	then
+		# Windows
+		NPROC="$NUMBER_OF_PROCESSORS"
+	else
+		NPROC=1
+	fi
+
+	echo $NPROC
+}
diff --git a/ci/lib.sh b/ci/lib.sh
index 9e38c893890..80e89f89b7f 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -1,16 +1,55 @@
 #!/bin/sh
 set -e
 
+# Usage
+CI_TYPE_HELP_COMMANDS='
+	# run "make all test" like the "linux-leaks" job
+	(eval $(jobname=linux-leaks ci/lib.sh --all) && make test)
+
+	# run "make all test" like the "linux-musl" job
+	(eval $(jobname=linux-musl ci/lib.sh --all) && make test)
+
+	# run "make test" like the "linux-TEST-vars" job (uses various GIT_TEST_* modes)
+	make && (eval $(jobname=linux-TEST-vars ci/lib.sh --test) && make test)
+
+	# run "make test" like the "linux-sha256" job
+	make && (eval $(jobname=linux-sha256 ci/lib.sh --test) && make test)
+'
+
+CI_TYPE_HELP="
+Running $0 outside of CI? You can use ci/lib.sh to set up your
+environment like a given CI job. E.g.:
+$CI_TYPE_HELP_COMMANDS
+Note that some of these (e.g. the linux-musl one) may not work as
+expected due to the CI job configuring a platform that may not match
+yours."
+
+usage() {
+	echo "usage: jobname=<job-name> [runs_on_pool=<pool-name>] $0 (--build | --test)" >&2
+	if test -z "$CI_TYPE"
+	then
+		echo "$CI_TYPE_HELP" >&2
+	fi
+	exit 1
+}
+
 # Helper libraries
 . ${0%/*}/lib-ci-type.sh
 
 # Parse options
+mode_all=
 mode_build=
 mode_test=
 mode_debug=
 while test $# != 0
 do
 	case "$1" in
+	--all)
+		echo "MODE: $1" >&2
+		mode_all=t
+		mode_build=t
+		mode_test=t
+		;;
 	--build)
 		echo "MODE: $1" >&2
 		mode_build=t
@@ -25,11 +64,11 @@ do
 		;;
 	-*)
 		echo "error: invalid option: $1" >&2
-		exit 1
+		usage
 		;;
 	*)
 		echo "error: invalid argument: $1" >&2
-		exit 1
+		usage
 		;;
 	esac
 	shift
@@ -39,13 +78,13 @@ done
 if test -z "$jobname"
 then
 	echo "error: must set a CI jobname in the environment" >&2
-	exit 1
+	usage
 fi
 
-if test "$mode_test$mode_build" != "t"
+if test "$mode_test$mode_build" != "t" && test -z "$mode_all"
 then
 	echo "error: need one mode, e.g. --build or --test" >&2
-	exit 1
+	usage
 fi
 
 # Show our configuration
@@ -65,13 +104,13 @@ setenv () {
 	do
 		case "$1" in
 		--build)
-			if test -z "$mode_build"
+			if test -z "$mode_build$mode_all"
 			then
 				skip=t
 			fi
 			;;
 		--test)
-			if test -z "$mode_test"
+			if test -z "$mode_test$mode_all"
 			then
 				skip=t
 			fi
@@ -103,6 +142,10 @@ setenv () {
 	if test -n "$GITHUB_ENV"
 	then
 		echo "$key=$val" >>"$GITHUB_ENV"
+	elif test -z "$CI_TYPE"
+	then
+		echo "$key=\"$val\""
+		echo "export $key"
 	fi
 
 	echo "SET: '$key=$val'" >&2
@@ -113,10 +156,25 @@ CC=
 
 # How many jobs to run in parallel?
 NPROC=10
+case "$CI_TYPE" in
+'')
+	. ${0%/*}/lib-online_cpus.sh
+	NPROC=$(online_cpus)
+
+	if test -n "$MAKEFLAGS"
+	then
+		COMMON_MAKEFLAGS="$MAKEFLAGS"
+	else
+		COMMON_MAKEFLAGS=--jobs=$NPROC
+	fi
+	;;
+*)
+	# For "--test" we carry the MAKEFLAGS over from earlier steps, except
+	# in stand-alone jobs which will use $COMMON_MAKEFLAGS.
+	COMMON_MAKEFLAGS=--jobs=$NPROC
+	;;
+esac
 
-# For "--test" we carry the MAKEFLAGS over from earlier steps, except
-# in stand-alone jobs which will use $COMMON_MAKEFLAGS.
-COMMON_MAKEFLAGS=--jobs=$NPROC
 
 # Clear MAKEFLAGS that may come from the outside world.
 MAKEFLAGS=$COMMON_MAKEFLAGS
@@ -136,6 +194,8 @@ github-actions)
 	GIT_TEST_OPTS="--no-chain-lint --no-bin-wrappers $GIT_TEST_OPTS"
 	setenv --test GIT_TEST_OPTS "$GIT_TEST_OPTS"
 	;;
+'')
+	;;
 *)
 	echo "Unhandled CI type: $CI_TYPE" >&2
 	exit 1
diff --git a/ci/print-test-failures.sh b/ci/print-test-failures.sh
index 29f8c332eca..ec395c79ccd 100755
--- a/ci/print-test-failures.sh
+++ b/ci/print-test-failures.sh
@@ -36,10 +36,6 @@ do
 			cp "${TEST_EXIT%.exit}.out" failed-test-artifacts/
 			tar czf failed-test-artifacts/"$test_name".trash.tar.gz "$trash_dir"
 			;;
-		*)
-			echo "Unhandled CI type: $CI_TYPE" >&2
-			exit 1
-			;;
 		esac
 	fi
 done
