Index: lib/Support/Unix/Memory.inc
===================================================================
--- lib/Support/Unix/Memory.inc
+++ lib/Support/Unix/Memory.inc
@@ -195,6 +195,10 @@
 #if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
   void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_EXEC,
                     flags, fd, 0);
+#elif defined(__NetBSD__) && defined(PROT_MPROTECT)
+  void *pa =
+      ::mmap(start, PageSize * NumPages,
+             PROT_READ | PROT_WRITE | PROT_MPROTECT(PROT_EXEC), flags, fd, 0);
 #else
   void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
                     flags, fd, 0);