diff --git a/ChangeLog b/ChangeLog
index 01bfa109d..7d8f7f238 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-01-31  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
+
+	Sync from gcc:
+	* configure.ac: Add "recommended" version checks for GMP/MPC.
+	Update recommended GMP/MPFR/MPC versions.
+	* configure: Regenerate.
+
 2010-01-25  Joern Rennecke  <amylaar@spamcop.net>
 
 	gcc PR libstdc++/36101, gcc PR libstdc++/42813
diff --git a/configure b/configure
index ad16b8f25..e6cde58bf 100755
--- a/configure
+++ b/configure
@@ -5466,18 +5466,38 @@ if test -d ${srcdir}/gcc && test "x$have_gmp" = xno; then
   have_gmp=yes
   saved_CFLAGS="$CFLAGS"
   CFLAGS="$CFLAGS $gmpinc"
-  # Check GMP actually works
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for correct version of gmp.h" >&5
-$as_echo_n "checking for correct version of gmp.h... " >&6; }
-
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+  # Check for the recommended and required versions of GMP.
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for the correct version of gmp.h" >&5
+$as_echo_n "checking for the correct version of gmp.h... " >&6; }
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include "gmp.h"
 int
 main ()
 {
 
-  #if __GNU_MP_VERSION < 4 || (__GNU_MP_VERSION == 4 && __GNU_MP_VERSION_MINOR < 2)
+  #define GCC_GMP_VERSION_NUM(a,b,c) (((a) << 16L) | ((b) << 8) | (c))
+  #define GCC_GMP_VERSION GCC_GMP_VERSION_NUM(__GNU_MP_VERSION,__GNU_MP_VERSION_MINOR,__GNU_MP_VERSION_PATCHLEVEL)
+  #if GCC_GMP_VERSION < GCC_GMP_VERSION_NUM(4,2,0)
+  choke me
+  #endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <gmp.h>
+int
+main ()
+{
+
+  #define GCC_GMP_VERSION_NUM(a,b,c) (((a) << 16L) | ((b) << 8) | (c))
+  #define GCC_GMP_VERSION GCC_GMP_VERSION_NUM(__GNU_MP_VERSION,__GNU_MP_VERSION_MINOR,__GNU_MP_VERSION_PATCHLEVEL)
+  #if GCC_GMP_VERSION < GCC_GMP_VERSION_NUM(4,3,2)
   choke me
   #endif
 
@@ -5488,6 +5508,11 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: buggy but acceptable" >&5
+$as_echo "buggy but acceptable" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }; have_gmp=no
@@ -5496,8 +5521,9 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
   # If we have GMP, check the MPFR version.
   if test x"$have_gmp" = xyes; then
-        { $as_echo "$as_me:${as_lineno-$LINENO}: checking for correct version of mpfr.h" >&5
-$as_echo_n "checking for correct version of mpfr.h... " >&6; }
+    # Check for the recommended and required versions of MPFR.
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for the correct version of mpfr.h" >&5
+$as_echo_n "checking for the correct version of mpfr.h... " >&6; }
     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <gmp.h>
@@ -5523,7 +5549,7 @@ int
 main ()
 {
 
-    #if MPFR_VERSION < MPFR_VERSION_NUM(2,3,2)
+    #if MPFR_VERSION < MPFR_VERSION_NUM(2,4,2)
     choke me
     #endif
 
@@ -5548,6 +5574,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
   # Check for the MPC header version.
   if test x"$have_gmp" = xyes ; then
+    # Check for the recommended and required versions of MPC.
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for the correct version of mpc.h" >&5
 $as_echo_n "checking for the correct version of mpc.h... " >&6; }
     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -5557,7 +5584,23 @@ int
 main ()
 {
 
-    #if MPC_VERSION < MPC_VERSION_NUM (0,8,0)
+    #if MPC_VERSION < MPC_VERSION_NUM(0,8,0)
+    choke me
+    #endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <mpc.h>
+int
+main ()
+{
+
+    #if MPC_VERSION < MPC_VERSION_NUM(0,8,1)
     choke me
     #endif
 
@@ -5568,6 +5611,11 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: buggy but acceptable" >&5
+$as_echo "buggy but acceptable" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }; have_gmp=no
@@ -5624,8 +5672,10 @@ rm -f core conftest.err conftest.$ac_objext \
 
   CFLAGS="$saved_CFLAGS"
 
+# The library versions listed in the error message below should match
+# the HARD-minimums enforced above.
   if test x$have_gmp != xyes; then
-    as_fn_error "Building GCC requires GMP 4.2+, MPFR 2.3.2+ and MPC 0.8.0+.
+    as_fn_error "Building GCC requires GMP 4.2+, MPFR 2.3.1+ and MPC 0.8.0+.
 Try the --with-gmp, --with-mpfr and/or --with-mpc options to specify
 their locations.  Source code for these libraries can be found at
 their respective hosting sites as well as at
diff --git a/configure.ac b/configure.ac
index 75af4e513..be6337bf5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1341,18 +1341,27 @@ if test -d ${srcdir}/gcc && test "x$have_gmp" = xno; then
   have_gmp=yes
   saved_CFLAGS="$CFLAGS"
   CFLAGS="$CFLAGS $gmpinc"
-  # Check GMP actually works
-  AC_MSG_CHECKING([for correct version of gmp.h])
+  # Check for the recommended and required versions of GMP.
+  AC_MSG_CHECKING([for the correct version of gmp.h])
   AC_TRY_COMPILE([#include "gmp.h"],[
-  #if __GNU_MP_VERSION < 4 || (__GNU_MP_VERSION == 4 && __GNU_MP_VERSION_MINOR < 2)
+  #define GCC_GMP_VERSION_NUM(a,b,c) (((a) << 16L) | ((b) << 8) | (c))
+  #define GCC_GMP_VERSION GCC_GMP_VERSION_NUM(__GNU_MP_VERSION,__GNU_MP_VERSION_MINOR,__GNU_MP_VERSION_PATCHLEVEL)
+  #if GCC_GMP_VERSION < GCC_GMP_VERSION_NUM(4,2,0)
   choke me
   #endif
-  ], [AC_MSG_RESULT([yes])], [AC_MSG_RESULT([no]); have_gmp=no])
+  ], AC_TRY_COMPILE([#include <gmp.h>],[
+  #define GCC_GMP_VERSION_NUM(a,b,c) (((a) << 16L) | ((b) << 8) | (c))
+  #define GCC_GMP_VERSION GCC_GMP_VERSION_NUM(__GNU_MP_VERSION,__GNU_MP_VERSION_MINOR,__GNU_MP_VERSION_PATCHLEVEL)
+  #if GCC_GMP_VERSION < GCC_GMP_VERSION_NUM(4,3,2)
+  choke me
+  #endif
+  ], [AC_MSG_RESULT([yes])], [AC_MSG_RESULT([buggy but acceptable])]),
+   [AC_MSG_RESULT([no]); have_gmp=no])
 
   # If we have GMP, check the MPFR version.
   if test x"$have_gmp" = xyes; then
-    dnl MPFR 2.3.1 is acceptable, but MPFR 2.3.2 is better.
-    AC_MSG_CHECKING([for correct version of mpfr.h])
+    # Check for the recommended and required versions of MPFR.
+    AC_MSG_CHECKING([for the correct version of mpfr.h])
     AC_TRY_COMPILE([#include <gmp.h>
     #include <mpfr.h>],[
     #if MPFR_VERSION < MPFR_VERSION_NUM(2,3,1)
@@ -1360,7 +1369,7 @@ if test -d ${srcdir}/gcc && test "x$have_gmp" = xno; then
     #endif
     ], AC_TRY_COMPILE([#include <gmp.h>
     #include <mpfr.h>],[
-    #if MPFR_VERSION < MPFR_VERSION_NUM(2,3,2)
+    #if MPFR_VERSION < MPFR_VERSION_NUM(2,4,2)
     choke me
     #endif
     ], [AC_MSG_RESULT([yes])], [AC_MSG_RESULT([buggy but acceptable])]),
@@ -1369,12 +1378,18 @@ if test -d ${srcdir}/gcc && test "x$have_gmp" = xno; then
 
   # Check for the MPC header version.
   if test x"$have_gmp" = xyes ; then
+    # Check for the recommended and required versions of MPC.
     AC_MSG_CHECKING([for the correct version of mpc.h])
     AC_TRY_COMPILE([#include <mpc.h>],[
-    #if MPC_VERSION < MPC_VERSION_NUM (0,8,0)
+    #if MPC_VERSION < MPC_VERSION_NUM(0,8,0)
     choke me
     #endif
-    ], [AC_MSG_RESULT([yes])], [AC_MSG_RESULT([no]); have_gmp=no])
+    ], AC_TRY_COMPILE([#include <mpc.h>],[
+    #if MPC_VERSION < MPC_VERSION_NUM(0,8,1)
+    choke me
+    #endif
+    ], [AC_MSG_RESULT([yes])], [AC_MSG_RESULT([buggy but acceptable])]),
+     [AC_MSG_RESULT([no]); have_gmp=no])
   fi
 
   # Now check the MPFR library.
@@ -1406,8 +1421,10 @@ if test -d ${srcdir}/gcc && test "x$have_gmp" = xno; then
 
   CFLAGS="$saved_CFLAGS"
 
+# The library versions listed in the error message below should match
+# the HARD-minimums enforced above.
   if test x$have_gmp != xyes; then
-    AC_MSG_ERROR([Building GCC requires GMP 4.2+, MPFR 2.3.2+ and MPC 0.8.0+.
+    AC_MSG_ERROR([Building GCC requires GMP 4.2+, MPFR 2.3.1+ and MPC 0.8.0+.
 Try the --with-gmp, --with-mpfr and/or --with-mpc options to specify
 their locations.  Source code for these libraries can be found at
 their respective hosting sites as well as at