diff --git a/src/util/u_memset.h b/src/util/u_memset.h
index df8cf80b64a..46a43e54c4a 100644
--- a/src/util/u_memset.h
+++ b/src/util/u_memset.h
@@ -45,3 +45,23 @@ util_memset32(void *s, uint32_t ui, size_t n)
    return s;
 #endif
 }
+
+static inline void *
+util_memset64(void *s, uint64_t ui, size_t n)
+{
+#if defined(PIPE_CC_GCC) && defined(PIPE_ARCH_X86_64)
+   long d0, d1;
+   __asm__ volatile("rep\n\t"
+                    "stosq"
+                    : "=&c" (d0), "=&D" (d1)
+                    : "a" (ui), "1" (s), "0" (n)
+                    : "memory");
+   return s;
+#else
+   uint64_t *xs = (uint64_t *)s;
+   while (n--)
+      *xs++ = ui;
+   return s;
+#endif
+
+}