diff --git a/configure b/configure
index 8b8dfe15..c4d1e8dc 100755
--- a/configure
+++ b/configure
@@ -6898,7 +6898,14 @@ s390*-*linux*|s390*-*tpf*|sparc*-*linux*)
 	    LD="${LD-ld} -m elf_i386_fbsd"
 	    ;;
 	  x86_64-*linux*)
-	    LD="${LD-ld} -m elf_i386"
+	    case `/usr/bin/file conftest.o` in
+	      *x86-64*)
+	         LD="${LD-ld} -m elf32_x86_64"
+	         ;;
+	      *)
+	         LD="${LD-ld} -m elf_i386"
+	         ;;
+	    esac
 	    ;;
 	  ppc64-*linux*|powerpc64-*linux*)
 	    LD="${LD-ld} -m elf32ppclinux"
diff --git a/fficonfig.h.in b/fficonfig.h.in
index b54b273f..c77585da 100644
--- a/fficonfig.h.in
+++ b/fficonfig.h.in
@@ -20,6 +20,9 @@
 /* Cannot use PROT_EXEC on this target, so, we revert to alternative means */
 #undef FFI_EXEC_TRAMPOLINE_TABLE
 
+/* Define this if you want to enable pax emulated trampolines */
+#undef FFI_MMAP_EXEC_EMUTRAMP_PAX
+
 /* Cannot use malloc on this target, so, we revert to alternative means */
 #undef FFI_MMAP_EXEC_WRIT
 
@@ -160,6 +163,9 @@
 /* Define to 1 if you have the ANSI C header files. */
 #undef STDC_HEADERS
 
+/* Define if symbols are underscored. */
+#undef SYMBOL_UNDERSCORE
+
 /* Define this if you are using Purify and want to suppress spurious messages.
    */
 #undef USING_PURIFY
@@ -179,6 +185,9 @@
 # endif
 #endif
 
+/* Define to `unsigned int' if <sys/types.h> does not define. */
+#undef size_t
+
 
 #ifdef HAVE_HIDDEN_VISIBILITY_ATTRIBUTE
 #ifdef LIBFFI_ASM