diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index c06d6ae54944f40d90bfbeddd74b8fedf3f1a7ff..33cb70e372fb6484d53137d6e57fae903d265591 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,8 @@
+2013-03-27  Kai Tietz  <ktietz@redhat.com>
+
+	* crossconfig.m4: Add support for cygwin x64 target.
+	* configure: Regenerated.
+
 2013-03-25  Kai Tietz  <ktietz@redhat.com>
 
 	* testsuite/18_support/50594.cc: For mingw-targets use only static
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index f40ddcff99e334905af35cb4e36d59b03526deaa..d867af37114502b877a312d4fa5f44775586a12c 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -3530,11 +3530,11 @@ MAKEINFO=${MAKEINFO-"${am_missing_run}makeinfo"}
 
 # We need awk for the "check" target.  The system "awk" is bad on
 # some platforms.
-# Always define AMTAR for backward compatibility.
+# Always define AMTAR for backward compatibility.  Yes, it's still used
+# in the wild :-(  We should find a proper way to deprecate it ...
+AMTAR='$${TAR-tar}'
 
-AMTAR=${AMTAR-"${am_missing_run}tar"}
-
-am__tar='${AMTAR} chof - "$$tardir"'; am__untar='${AMTAR} xf -'
+am__tar='$${TAR-tar} chof - "$$tardir"' am__untar='$${TAR-tar} xf -'
 
 
 
@@ -46017,7 +46017,7 @@ $as_echo "#define HAVE_TLS 1" >>confdefs.h
 	;;
     esac
     ;;
-  *-linux* | *-uclinux* | *-gnu* | *-kfreebsd*-gnu | *-knetbsd*-gnu)
+  *-linux* | *-uclinux* | *-gnu* | *-kfreebsd*-gnu | *-knetbsd*-gnu | *-cygwin*)
 
   # All these tests are for C++; save the language and the compiler flags.
   # The CXXFLAGS thing is suspicious, but based on similar bits previously
diff --git a/libstdc++-v3/crossconfig.m4 b/libstdc++-v3/crossconfig.m4
index 943ea676ea2730c1ec3541ff3b447d38ce93afa1..0112f6fa5c39d115d109dbd59cd61b1f705f8d5b 100644
--- a/libstdc++-v3/crossconfig.m4
+++ b/libstdc++-v3/crossconfig.m4
@@ -141,7 +141,7 @@ case "${host}" in
 	;;
     esac
     ;;
-  *-linux* | *-uclinux* | *-gnu* | *-kfreebsd*-gnu | *-knetbsd*-gnu)
+  *-linux* | *-uclinux* | *-gnu* | *-kfreebsd*-gnu | *-knetbsd*-gnu | *-cygwin*)
     GLIBCXX_CHECK_COMPILER_FEATURES
     GLIBCXX_CHECK_LINKER_FEATURES
     GLIBCXX_CHECK_MATH_SUPPORT