diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index b2237e6d48f..95918e2f52b 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,10 @@
+2010-08-24  Richard Henderson  <rth@redhat.com>
+
+	PR bootstrap/45376
+	* configure.ac (HAVE_SSE4): New check.
+	* configure, config.in: Rebuild.
+	* lex.c (search_line_sse42): Omit if !HAVE_SSE4.
+
 2010-08-24  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	* lex.c [__sun__ && __svr4__]: Disable init_vectorized_lexer
diff --git a/libcpp/config.in b/libcpp/config.in
index 95606c18abf..29d4501821a 100644
--- a/libcpp/config.in
+++ b/libcpp/config.in
@@ -185,6 +185,9 @@
 /* Define to 1 if you have the `putc_unlocked' function. */
 #undef HAVE_PUTC_UNLOCKED
 
+/* Define to 1 if you can assemble SSE4 insns. */
+#undef HAVE_SSE4
+
 /* Define to 1 if you have the <stddef.h> header file. */
 #undef HAVE_STDDEF_H
 
diff --git a/libcpp/configure b/libcpp/configure
index a2ce1c3a70a..012ee41c819 100755
--- a/libcpp/configure
+++ b/libcpp/configure
@@ -7209,6 +7209,27 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+case $target in
+  i?86-* | x86_64-*)
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+asm ("pcmpestri %0, %%xmm0, %%xmm1" : : "i"(0))
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+
+$as_echo "#define HAVE_SSE4 1" >>confdefs.h
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+esac
+
 # Output.
 
 ac_config_headers="$ac_config_headers config.h:config.in"
diff --git a/libcpp/configure.ac b/libcpp/configure.ac
index 1250f495a9d..8082117f2d6 100644
--- a/libcpp/configure.ac
+++ b/libcpp/configure.ac
@@ -184,6 +184,13 @@ AC_DEFINE_UNQUOTED(HOST_WIDE_INT, $host_wide_int,
 [Define to the widest efficient host integer type at least
    as wide as the target's size_t type.])
 
+case $target in
+  i?86-* | x86_64-*)
+    AC_TRY_COMPILE([], [asm ("pcmpestri %0, %%xmm0, %%xmm1" : : "i"(0))],
+      [AC_DEFINE([HAVE_SSE4], [1],
+		 [Define to 1 if you can assemble SSE4 insns.])])
+esac
+
 # Output.
 
 AC_CONFIG_HEADERS(config.h:config.in, [echo timestamp > stamp-h1])
diff --git a/libcpp/lex.c b/libcpp/lex.c
index a94e57282d8..2e962a70bb9 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -410,6 +410,7 @@ search_line_sse2 (const uchar *s, const uchar *end ATTRIBUTE_UNUSED)
   return (const uchar *)p + found;
 }
 
+#ifdef HAVE_SSE4
 /* A version of the fast scanner using SSE 4.2 vectorized string insns.  */
 
 static const uchar *
@@ -464,6 +465,11 @@ search_line_sse42 (const uchar *s, const uchar *end)
   return s + index;
 }
 
+#else
+/* Work around out-dated assemblers without sse4 support.  */
+#define search_line_sse42 search_line_sse2
+#endif
+
 /* Check the CPU capabilities.  */
 
 #include "../gcc/config/i386/cpuid.h"