diff --git a/hypervisor/arch/x86/lib/memory.c b/hypervisor/arch/x86/lib/memory.c
index 84e5068c6..5e31c2079 100644
--- a/hypervisor/arch/x86/lib/memory.c
+++ b/hypervisor/arch/x86/lib/memory.c
@@ -4,39 +4,6 @@
  */
 #include <types.h>
 
-static inline void memcpy_erms(void *d, const void *s, size_t slen)
-{
-	asm volatile ("rep; movsb"
-		: "=&D"(d), "=&S"(s)
-		: "c"(slen), "0" (d), "1" (s)
-		: "memory");
-}
-
-/*
- * @brief  Copies at most slen bytes from src address to dest address, up to dmax.
- *
- *   INPUTS
- *
- * @param[in] d        pointer to Destination address
- * @param[in] dmax     maximum  length of dest
- * @param[in] s        pointer to Source address
- * @param[in] slen     maximum number of bytes of src to copy
- *
- * @return pointer to destination address.
- *
- * @pre d and s will not overlap.
- */
-void *memcpy_s(void *d, size_t dmax, const void *s, size_t slen)
-{
-	if ((slen != 0U) && (dmax != 0U) && (dmax >= slen)) {
-		/* same memory block, no need to copy */
-		if (d != s) {
-			memcpy_erms(d, s, slen);
-		}
-	}
-	return d;
-}
-
 static inline void memset_erms(void *base, uint8_t v, size_t n)
 {
 	asm volatile("rep ; stosb"
@@ -56,3 +23,39 @@ void *memset(void *base, uint8_t v, size_t n)
 
 	return base;
 }
+
+static inline void memcpy_erms(void *d, const void *s, size_t slen)
+{
+	asm volatile ("rep; movsb"
+		: "=&D"(d), "=&S"(s)
+		: "c"(slen), "0" (d), "1" (s)
+		: "memory");
+}
+
+/*
+ * @brief  Copies at most slen bytes from src address to dest address, up to dmax.
+ *
+ *   INPUTS
+ *
+ * @param[in] d        pointer to Destination address
+ * @param[in] dmax     maximum  length of dest
+ * @param[in] s        pointer to Source address
+ * @param[in] slen     maximum number of bytes of src to copy
+ *
+ * @return 0 for success and -1 for runtime-constraint violation.
+ */
+int32_t memcpy_s(void *d, size_t dmax, const void *s, size_t slen)
+{
+	int32_t ret = -1;
+
+	if ((d != NULL) && (s != NULL) && (dmax >= slen) && ((d > (s + slen)) || (s > (d + dmax)))) {
+		if (slen != 0U) {
+			memcpy_erms(d, s, slen);
+		}
+		ret = 0;
+	} else {
+		(void)memset(d, 0U, dmax);
+	}
+
+	return ret;
+}
diff --git a/hypervisor/include/lib/rtl.h b/hypervisor/include/lib/rtl.h
index 475a6f93b..fe923b946 100644
--- a/hypervisor/include/lib/rtl.h
+++ b/hypervisor/include/lib/rtl.h
@@ -36,7 +36,7 @@ char *strncpy_s(char *d_arg, size_t dmax, const char *s_arg, size_t slen_arg);
 char *strchr(char *s_arg, char ch);
 size_t strnlen_s(const char *str_arg, size_t maxlen_arg);
 void *memset(void *base, uint8_t v, size_t n);
-void *memcpy_s(void *d, size_t dmax, const void *s, size_t slen);
+int32_t memcpy_s(void *d, size_t dmax, const void *s, size_t slen);
 int64_t strtol_deci(const char *nptr);
 uint64_t strtoul_hex(const char *nptr);
 char *strstr_s(const char *str1, size_t maxlen1,