diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index ba5c395d2d..dc95c34cc8 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -58,6 +58,12 @@
 #
 #     When set to "1" suggest all options, including options which are
 #     typically hidden (e.g. '--allow-empty' for 'git commit').
+#
+#   GIT_COMPLETION_IGNORE_CASE
+#
+#     When set, uses for-each-ref '--ignore-case' to find refs that match
+#     case insensitively, even on systems with case sensitive file systems
+#     (e.g., completing tag name "FOO" on "git checkout f<TAB>").
 
 case "$COMP_WORDBREAKS" in
 *:*) : great ;;
@@ -646,6 +652,7 @@ __git_heads ()
 	local pfx="${1-}" cur_="${2-}" sfx="${3-}"
 
 	__git for-each-ref --format="${pfx//\%/%%}%(refname:strip=2)$sfx" \
+			${GIT_COMPLETION_IGNORE_CASE+--ignore-case} \
 			"refs/heads/$cur_*" "refs/heads/$cur_*/**"
 }
 
@@ -659,6 +666,7 @@ __git_remote_heads ()
 	local pfx="${1-}" cur_="${2-}" sfx="${3-}"
 
 	__git for-each-ref --format="${pfx//\%/%%}%(refname:strip=2)$sfx" \
+			${GIT_COMPLETION_IGNORE_CASE+--ignore-case} \
 			"refs/remotes/$cur_*" "refs/remotes/$cur_*/**"
 }
 
@@ -669,6 +677,7 @@ __git_tags ()
 	local pfx="${1-}" cur_="${2-}" sfx="${3-}"
 
 	__git for-each-ref --format="${pfx//\%/%%}%(refname:strip=2)$sfx" \
+			${GIT_COMPLETION_IGNORE_CASE+--ignore-case} \
 			"refs/tags/$cur_*" "refs/tags/$cur_*/**"
 }
 
@@ -688,6 +697,7 @@ __git_dwim_remote_heads ()
 	# but only output if the branch name is unique
 	__git for-each-ref --format="$fer_pfx%(refname:strip=3)$sfx" \
 		--sort="refname:strip=3" \
+		${GIT_COMPLETION_IGNORE_CASE+--ignore-case} \
 		"refs/remotes/*/$cur_*" "refs/remotes/*/$cur_*/**" | \
 	uniq -u
 }
@@ -712,6 +722,7 @@ __git_refs ()
 	local format refs
 	local pfx="${3-}" cur_="${4-$cur}" sfx="${5-}"
 	local match="${4-}"
+	local umatch="${4-}"
 	local fer_pfx="${pfx//\%/%%}" # "escape" for-each-ref format specifiers
 
 	__git_find_repo_path
@@ -735,12 +746,19 @@ __git_refs ()
 		fi
 	fi
 
+	if test "${GIT_COMPLETION_IGNORE_CASE:+1}" = "1"
+	then
+		# uppercase with tr instead of ${match,^^} for bash 3.2 compatibility
+		umatch=$(echo "$match" | tr a-z A-Z 2>/dev/null || echo "$match")
+	fi
+
 	if [ "$list_refs_from" = path ]; then
 		if [[ "$cur_" == ^* ]]; then
 			pfx="$pfx^"
 			fer_pfx="$fer_pfx^"
 			cur_=${cur_#^}
 			match=${match#^}
+			umatch=${umatch#^}
 		fi
 		case "$cur_" in
 		refs|refs/*)
@@ -751,7 +769,7 @@ __git_refs ()
 		*)
 			for i in HEAD FETCH_HEAD ORIG_HEAD MERGE_HEAD REBASE_HEAD CHERRY_PICK_HEAD; do
 				case "$i" in
-				$match*)
+				$match*|$umatch*)
 					if [ -e "$dir/$i" ]; then
 						echo "$pfx$i$sfx"
 					fi
@@ -765,6 +783,7 @@ __git_refs ()
 			;;
 		esac
 		__git_dir="$dir" __git for-each-ref --format="$fer_pfx%($format)$sfx" \
+			${GIT_COMPLETION_IGNORE_CASE+--ignore-case} \
 			"${refs[@]}"
 		if [ -n "$track" ]; then
 			__git_dwim_remote_heads "$pfx" "$match" "$sfx"
@@ -784,15 +803,16 @@ __git_refs ()
 	*)
 		if [ "$list_refs_from" = remote ]; then
 			case "HEAD" in
-			$match*)	echo "${pfx}HEAD$sfx" ;;
+			$match*|$umatch*)	echo "${pfx}HEAD$sfx" ;;
 			esac
 			__git for-each-ref --format="$fer_pfx%(refname:strip=3)$sfx" \
+				${GIT_COMPLETION_IGNORE_CASE+--ignore-case} \
 				"refs/remotes/$remote/$match*" \
 				"refs/remotes/$remote/$match*/**"
 		else
 			local query_symref
 			case "HEAD" in
-			$match*)	query_symref="HEAD" ;;
+			$match*|$umatch*)	query_symref="HEAD" ;;
 			esac
 			__git ls-remote "$remote" $query_symref \
 				"refs/tags/$match*" "refs/heads/$match*" \
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 43de868b80..d6c0478d98 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -2255,6 +2255,36 @@ test_expect_success 'checkout completes ref names' '
 	EOF
 '
 
+test_expect_success 'checkout does not match ref names of a different case' '
+	test_completion "git checkout M" ""
+'
+
+test_expect_success 'checkout matches case insensitively with GIT_COMPLETION_IGNORE_CASE' '
+	(
+		GIT_COMPLETION_IGNORE_CASE=1 &&
+		test_completion "git checkout M" <<-\EOF
+		main Z
+		mybranch Z
+		mytag Z
+		EOF
+	)
+'
+
+test_expect_success 'checkout completes pseudo refs' '
+	test_completion "git checkout H" <<-\EOF
+	HEAD Z
+	EOF
+'
+
+test_expect_success 'checkout completes pseudo refs case insensitively with GIT_COMPLETION_IGNORE_CASE' '
+	(
+		GIT_COMPLETION_IGNORE_CASE=1 &&
+		test_completion "git checkout h" <<-\EOF
+		HEAD Z
+		EOF
+	)
+'
+
 test_expect_success 'git -C <path> checkout uses the right repo' '
 	test_completion "git -C subdir -C subsubdir -C .. -C ../otherrepo checkout b" <<-\EOF
 	branch-in-other Z