diff --git a/builtin/commit.c b/builtin/commit.c
index fa3e53232d..b57d8e4b82 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -34,6 +34,7 @@
 #include "mailmap.h"
 #include "help.h"
 #include "commit-reach.h"
+#include "commit-graph.h"
 
 static const char * const builtin_commit_usage[] = {
 	N_("git commit [<options>] [--] <pathspec>..."),
@@ -1652,6 +1653,9 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		      "new_index file. Check that disk is not full and quota is\n"
 		      "not exceeded, and then \"git reset HEAD\" to recover."));
 
+	if (git_env_bool(GIT_TEST_COMMIT_GRAPH, 0))
+		write_commit_graph_reachable(get_object_directory(), 0);
+
 	rerere(0);
 	run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 	run_commit_hook(use_editor, get_index_file(), "post-commit", NULL);
diff --git a/commit-graph.c b/commit-graph.c
index ae6cabb4cd..7f4519ec3b 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -213,8 +213,9 @@ static int prepare_commit_graph(struct repository *r)
 		return !!r->objects->commit_graph;
 	r->objects->commit_graph_attempted = 1;
 
-	if (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
-	    !config_value)
+	if (!git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
+	    (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
+	    !config_value))
 		/*
 		 * This repository is not configured to use commit graphs, so
 		 * do not load one. (But report commit_graph_attempted anyway
diff --git a/commit-graph.h b/commit-graph.h
index 698f09e2bc..b050476765 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -6,6 +6,8 @@
 #include "string-list.h"
 #include "cache.h"
 
+#define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH"
+
 struct commit;
 
 char *get_commit_graph_filename(const char *obj_dir);
diff --git a/t/README b/t/README
index 204b9f4cc5..3ea6c85460 100644
--- a/t/README
+++ b/t/README
@@ -323,6 +323,10 @@ GIT_TEST_VALIDATE_INDEX_CACHE_ENTRIES=<boolean> checks that cache-tree
 records are valid when the index is written out or after a merge. This
 is mostly to catch missing invalidation. Default is true.
 
+GIT_TEST_COMMIT_GRAPH=<boolean>, when true, forces the commit-graph to
+be written after every 'git commit' command, and overrides the
+'core.commitGraph' setting to true.
+
 Naming Tests
 ------------
 
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index 1281300664..b35bc89f1e 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -181,7 +181,7 @@ test_expect_success 'rev-list stops traversal at missing and promised commit' '
 
 	git -C repo config core.repositoryformatversion 1 &&
 	git -C repo config extensions.partialclone "arbitrary string" &&
-	git -C repo rev-list --exclude-promisor-objects --objects bar >out &&
+	GIT_TEST_COMMIT_GRAPH=0 git -C repo rev-list --exclude-promisor-objects --objects bar >out &&
 	grep $(git -C repo rev-parse bar) out &&
 	! grep $FOO out
 '
diff --git a/t/t5307-pack-missing-commit.sh b/t/t5307-pack-missing-commit.sh
index ae52a1882d..dacb440b27 100755
--- a/t/t5307-pack-missing-commit.sh
+++ b/t/t5307-pack-missing-commit.sh
@@ -24,11 +24,11 @@ test_expect_success 'check corruption' '
 '
 
 test_expect_success 'rev-list notices corruption (1)' '
-	test_must_fail git rev-list HEAD
+	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list HEAD
 '
 
 test_expect_success 'rev-list notices corruption (2)' '
-	test_must_fail git rev-list --objects HEAD
+	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list --objects HEAD
 '
 
 test_expect_success 'pack-objects notices corruption' '
diff --git a/t/t6011-rev-list-with-bad-commit.sh b/t/t6011-rev-list-with-bad-commit.sh
index e51eb41f4b..545b461e51 100755
--- a/t/t6011-rev-list-with-bad-commit.sh
+++ b/t/t6011-rev-list-with-bad-commit.sh
@@ -41,10 +41,9 @@ test_expect_success 'corrupt second commit object' \
    test_must_fail git fsck --full
    '
 
-test_expect_success 'rev-list should fail' \
-   '
-   test_must_fail git rev-list --all > /dev/null
-   '
+test_expect_success 'rev-list should fail' '
+	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list --all > /dev/null
+'
 
 test_expect_success 'git repack _MUST_ fail' \
    '
diff --git a/t/t6024-recursive-merge.sh b/t/t6024-recursive-merge.sh
index 3f59e58dfb..27c7de90ce 100755
--- a/t/t6024-recursive-merge.sh
+++ b/t/t6024-recursive-merge.sh
@@ -60,9 +60,9 @@ git update-index a1 &&
 GIT_AUTHOR_DATE="2006-12-12 23:00:08" git commit -m F
 '
 
-test_expect_success "combined merge conflicts" "
-	test_must_fail git merge -m final G
-"
+test_expect_success 'combined merge conflicts' '
+	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git merge -m final G
+'
 
 cat > expect << EOF
 <<<<<<< HEAD