diff --git a/test/lib/Makefile b/test/lib/Makefile
index a30f615aa9..aa2e66bc7f 100644
--- a/test/lib/Makefile
+++ b/test/lib/Makefile
@@ -11,6 +11,7 @@ obj-y += longjmp.o
 obj-$(CONFIG_CONSOLE_RECORD) += test_print.o
 obj-$(CONFIG_SSCANF) += sscanf.o
 obj-y += string.o
+obj-y += strlcat.o
 obj-$(CONFIG_ERRNO_STR) += test_errno_str.o
 obj-$(CONFIG_UT_LIB_ASN1) += asn1.o
 obj-$(CONFIG_UT_LIB_RSA) += rsa.o
diff --git a/test/lib/strlcat.c b/test/lib/strlcat.c
new file mode 100644
index 0000000000..ee61684c40
--- /dev/null
+++ b/test/lib/strlcat.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.1+
+/*
+ * Copyright (C) 2021 Sean Anderson <seanga2@gmail.com>
+ * Copyright (C) 2011-2021 Free Software Foundation, Inc.
+ *
+ * These tests adapted from glibc's string/test-strncat.c
+ */
+
+#include <common.h>
+#include <test/lib.h>
+#include <test/test.h>
+#include <test/ut.h>
+
+#define BUF_SIZE 4096
+char buf1[BUF_SIZE], buf2[BUF_SIZE];
+
+static int do_test_strlcat(struct unit_test_state *uts, int line, size_t align1,
+			   size_t align2, size_t len1, size_t len2, size_t n)
+{
+	char *s1, *s2;
+	size_t i, len, expected, actual;
+
+	align1 &= 7;
+	if (align1 + len1 >= BUF_SIZE)
+		return 0;
+	if (align1 + n > BUF_SIZE)
+		return 0;
+
+	align2 &= 7;
+	if (align2 + len1 + len2 >= BUF_SIZE)
+		return 0;
+	if (align2 + len1 + n > BUF_SIZE)
+		return 0;
+
+	s1 = buf1 + align1;
+	s2 = buf2 + align2;
+
+	for (i = 0; i < len1 - 1; i++)
+		s1[i] = 32 + 23 * i % (127 - 32);
+	s1[len1 - 1] = '\0';
+
+	for (i = 0; i < len2 - 1; i++)
+		s2[i] = 32 + 23 * i % (127 - 32);
+	s2[len2 - 1] = '\0';
+
+	expected = len2 < n ? min(len1 + len2 - 1, n) : n;
+	actual = strlcat(s2, s1, n);
+	if (expected != actual) {
+		ut_failf(uts, __FILE__, line, __func__,
+			 "strlcat(s2, s1, 2) == len2 < n ? min(len1 + len2, n) : n",
+			 "Expected %#lx (%ld), got %#lx (%ld)",
+			 expected, expected, actual, actual);
+		return CMD_RET_FAILURE;
+	}
+
+	len = min3(len1, n - len2, (size_t)0);
+	if (memcmp(s2 + len2, s1, len)) {
+		ut_failf(uts, __FILE__, line, __func__,
+			 "s2 + len1 == s1",
+			 "Expected \"%.*s\", got \"%.*s\"",
+			 (int)len, s1, (int)len, s2 + len2);
+		return CMD_RET_FAILURE;
+	}
+
+	i = min(n, len1 + len2 - 1) - 1;
+	if (len2 < n && s2[i] != '\0') {
+		ut_failf(uts, __FILE__, line, __func__,
+			 "n < len1 && s2[len2 + n] == '\\0'",
+			 "Expected s2[%ld] = '\\0', got %d ('%c')",
+			 i, s2[i], s2[i]);
+		return CMD_RET_FAILURE;
+	}
+
+	return 0;
+}
+
+#define test_strlcat(align1, align2, len1, len2, n) do { \
+	int ret = do_test_strlcat(uts, __LINE__, align1, align2, len1, len2, \
+				  n); \
+	if (ret) \
+		return ret; \
+} while (0)
+
+static int lib_test_strlcat(struct unit_test_state *uts)
+{
+	size_t i, n;
+
+	test_strlcat(0, 2, 2, 2, SIZE_MAX);
+	test_strlcat(0, 0, 4, 4, SIZE_MAX);
+	test_strlcat(4, 0, 4, 4, SIZE_MAX);
+	test_strlcat(0, 0, 8, 8, SIZE_MAX);
+	test_strlcat(0, 8, 8, 8, SIZE_MAX);
+
+	for (i = 1; i < 8; i++) {
+		test_strlcat(0, 0, 8 << i, 8 << i, SIZE_MAX);
+		test_strlcat(8 - i, 2 * i, 8 << i, 8 << i, SIZE_MAX);
+		test_strlcat(0, 0, 8 << i, 2 << i, SIZE_MAX);
+		test_strlcat(8 - i, 2 * i, 8 << i, 2 << i, SIZE_MAX);
+
+		test_strlcat(i, 2 * i, 8 << i, 1, SIZE_MAX);
+		test_strlcat(2 * i, i, 8 << i, 1, SIZE_MAX);
+		test_strlcat(i, i, 8 << i, 10, SIZE_MAX);
+	}
+
+	for (n = 2; n <= 2048; n *= 4) {
+		test_strlcat(0, 2, 2, 2, n);
+		test_strlcat(0, 0, 4, 4, n);
+		test_strlcat(4, 0, 4, 4, n);
+		test_strlcat(0, 0, 8, 8, n);
+		test_strlcat(0, 8, 8, 8, n);
+
+		for (i = 1; i < 8; i++) {
+			test_strlcat(0, 0, 8 << i, 8 << i, n);
+			test_strlcat(8 - i, 2 * i, 8 << i, 8 << i, n);
+			test_strlcat(0, 0, 8 << i, 2 << i, n);
+			test_strlcat(8 - i, 2 * i, 8 << i, 2 << i, n);
+
+			test_strlcat(i, 2 * i, 8 << i, 1, n);
+			test_strlcat(2 * i, i, 8 << i, 1, n);
+			test_strlcat(i, i, 8 << i, 10, n);
+		}
+	}
+
+	return 0;
+}
+LIB_TEST(lib_test_strlcat, 0);