diff --git a/qemu/include/qemu/bswap.h b/qemu/include/qemu/bswap.h
index 78903d44..ce6934ef 100644
--- a/qemu/include/qemu/bswap.h
+++ b/qemu/include/qemu/bswap.h
@@ -300,51 +300,57 @@ static inline void stb_p(void *ptr, uint8_t v)
     *(uint8_t *)ptr = v;
 }
 
-/* Any compiler worth its salt will turn these memcpy into native unaligned
-   operations.  Thus we don't need to play games with packed attributes, or
-   inline byte-by-byte stores.  */
+/*
+ * Any compiler worth its salt will turn these memcpy into native unaligned
+ * operations.  Thus we don't need to play games with packed attributes, or
+ * inline byte-by-byte stores.
+ * Some compilation environments (eg some fortify-source implementations)
+ * may intercept memcpy() in a way that defeats the compiler optimization,
+ * though, so we use __builtin_memcpy() to give ourselves the best chance
+ * of good performance.
+ */
 
 static inline int lduw_he_p(const void *ptr)
 {
     uint16_t r;
-    memcpy(&r, ptr, sizeof(r));
+    __builtin_memcpy(&r, ptr, sizeof(r));
     return r;
 }
 
 static inline int ldsw_he_p(const void *ptr)
 {
     int16_t r;
-    memcpy(&r, ptr, sizeof(r));
+    __builtin_memcpy(&r, ptr, sizeof(r));
     return r;
 }
 
 static inline void stw_he_p(void *ptr, uint16_t v)
 {
-    memcpy(ptr, &v, sizeof(v));
+    __builtin_memcpy(ptr, &v, sizeof(v));
 }
 
 static inline int ldl_he_p(const void *ptr)
 {
     int32_t r;
-    memcpy(&r, ptr, sizeof(r));
+    __builtin_memcpy(&r, ptr, sizeof(r));
     return r;
 }
 
 static inline void stl_he_p(void *ptr, uint32_t v)
 {
-    memcpy(ptr, &v, sizeof(v));
+    __builtin_memcpy(ptr, &v, sizeof(v));
 }
 
 static inline uint64_t ldq_he_p(const void *ptr)
 {
     uint64_t r;
-    memcpy(&r, ptr, sizeof(r));
+    __builtin_memcpy(&r, ptr, sizeof(r));
     return r;
 }
 
 static inline void stq_he_p(void *ptr, uint64_t v)
 {
-    memcpy(ptr, &v, sizeof(v));
+    __builtin_memcpy(ptr, &v, sizeof(v));
 }
 
 static inline int lduw_le_p(const void *ptr)