--- a/configure.in
+++ b/configure.in
@@ -1973,17 +1973,16 @@ ia64*-hpux*)
     i*86-*)
         if test "$HAVE_64BIT_OS"; then
             AC_MSG_ERROR([You are targeting i386 but using the 64-bit compiler.])
         fi
 
         if test $_MSC_VER -ge 1400; then
             LDFLAGS="$LDFLAGS -SAFESEH"
         fi
-    	AC_CHECK_HEADERS(mmintrin.h)
     	AC_DEFINE(_X86_)
 	;;
     alpha-*)
     	AC_DEFINE(_ALPHA_)
 	;;
     mips-*)
     	AC_DEFINE(_MIPS_)
 	;;
@@ -2751,21 +2750,16 @@ AC_CHECK_HEADERS(sys/byteorder.h compat.
 AC_CHECK_HEADERS(sys/bitypes.h memory.h unistd.h)
 AC_CHECK_HEADERS(gnu/libc-version.h nl_types.h)
 AC_CHECK_HEADERS(malloc.h)
 AC_CHECK_HEADERS(X11/XKBlib.h)
 
 dnl These are all the places some variant of statfs can be hiding.
 AC_CHECK_HEADERS(sys/statvfs.h sys/statfs.h sys/vfs.h sys/mount.h)
 
-dnl Try for MMX support
-dnl NB - later gcc versions require -mmmx for this header to be successfully
-dnl included (or another option which implies it, such as -march=pentium-mmx)
-AC_CHECK_HEADERS(mmintrin.h)
-
 dnl Check whether the compiler supports the new-style C++ standard
 dnl library headers (i.e. <new>) or needs the old "new.h"
 AC_LANG_CPLUSPLUS
 NEW_H=new.h
 AC_CHECK_HEADER(new, [NEW_H=new])
 AC_DEFINE_UNQUOTED(NEW_H, <$NEW_H>)
 AC_LANG_C