diff --git a/attr.c b/attr.c
index 38ecd2fff3..f9316d14ba 100644
--- a/attr.c
+++ b/attr.c
@@ -708,10 +708,25 @@ static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
 	FILE *fp = fopen_or_warn(path, "r");
 	struct attr_stack *res;
 	int lineno = 0;
+	int fd;
+	struct stat st;
 
 	if (!fp)
 		return NULL;
-	res = xcalloc(1, sizeof(*res));
+
+	fd = fileno(fp);
+	if (fstat(fd, &st)) {
+		warning_errno(_("cannot fstat gitattributes file '%s'"), path);
+		fclose(fp);
+		return NULL;
+	}
+	if (st.st_size >= ATTR_MAX_FILE_SIZE) {
+		warning(_("ignoring overly large gitattributes file '%s'"), path);
+		fclose(fp);
+		return NULL;
+	}
+
+	CALLOC_ARRAY(res, 1);
 	while (strbuf_getline(&buf, fp) != EOF) {
 		if (!lineno && starts_with(buf.buf, utf8_bom))
 			strbuf_remove(&buf, 0, strlen(utf8_bom));
@@ -730,13 +745,18 @@ static struct attr_stack *read_attr_from_index(const struct index_state *istate,
 	struct attr_stack *res;
 	char *buf, *sp;
 	int lineno = 0;
+	size_t size;
 
 	if (!istate)
 		return NULL;
 
-	buf = read_blob_data_from_index(istate, path, NULL);
+	buf = read_blob_data_from_index(istate, path, &size);
 	if (!buf)
 		return NULL;
+	if (size >= ATTR_MAX_FILE_SIZE) {
+		warning(_("ignoring overly large gitattributes blob '%s'"), path);
+		return NULL;
+	}
 
 	res = xcalloc(1, sizeof(*res));
 	for (sp = buf; *sp; ) {
diff --git a/attr.h b/attr.h
index df9a75da55..5970f930fd 100644
--- a/attr.h
+++ b/attr.h
@@ -113,6 +113,12 @@
  */
 #define ATTR_MAX_LINE_LENGTH 2048
 
+ /**
+  * The maximum size of the giattributes file. If the file exceeds this size we
+  * will ignore it.
+  */
+#define ATTR_MAX_FILE_SIZE (100 * 1024 * 1024)
+
 struct index_state;
 
 /**
diff --git a/t/t0003-attributes.sh b/t/t0003-attributes.sh
index 7d68e6a56e..9d9aa2855d 100755
--- a/t/t0003-attributes.sh
+++ b/t/t0003-attributes.sh
@@ -361,6 +361,14 @@ test_expect_success 'large attributes line ignores trailing content in tree' '
 	test_must_be_empty actual
 '
 
+test_expect_success EXPENSIVE 'large attributes file ignored in tree' '
+	test_when_finished "rm .gitattributes" &&
+	dd if=/dev/zero of=.gitattributes bs=101M count=1 2>/dev/null &&
+	git check-attr --all path >/dev/null 2>err &&
+	echo "warning: ignoring overly large gitattributes file ${SQ}.gitattributes${SQ}" >expect &&
+	test_cmp expect err
+'
+
 test_expect_success 'large attributes line ignored in index' '
 	test_when_finished "git update-index --remove .gitattributes" &&
 	blob=$(printf "path %02043d" 1 | git hash-object -w --stdin) &&
@@ -381,4 +389,13 @@ test_expect_success 'large attributes line ignores trailing content in index' '
 	test_must_be_empty actual
 '
 
+test_expect_success EXPENSIVE 'large attributes file ignored in index' '
+	test_when_finished "git update-index --remove .gitattributes" &&
+	blob=$(dd if=/dev/zero bs=101M count=1 2>/dev/null | git hash-object -w --stdin) &&
+	git update-index --add --cacheinfo 100644,$blob,.gitattributes &&
+	git check-attr --cached --all path >/dev/null 2>err &&
+	echo "warning: ignoring overly large gitattributes blob ${SQ}.gitattributes${SQ}" >expect &&
+	test_cmp expect err
+'
+
 test_done