Index: libgcc/config/darwin-crt-tm.c
===================================================================
--- libgcc/config/darwin-crt-tm.c	(revision 195764)
+++ libgcc/config/darwin-crt-tm.c	(working copy)
@@ -103,9 +103,12 @@ void __doTMdeRegistrations (void)
     _ITM_deregisterTMCloneTable (tmct);
 }
 
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && \
+            __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__  < 1060
+
 /* Provide dummy functions to satisfy linkage for versions of the Darwin 
    tool-chain that that can't handle undefined weak refs at the link stage.
-   ??? Define these dummy functions only when !HAVE_ELF_STYLE_WEAKREF. */
+   Don't define for 10.6 or later with faster weak-symbol coalescing. */
 
 extern void *__cxa_allocate_exception (size_t) WEAK;
 extern void __cxa_throw (void *, void *, void *) WEAK;
@@ -144,5 +147,5 @@ void _ZdlPvRKSt9nothrow_t (void * a UNUS
 void *_ZnaXRKSt9nothrow_t (size_t s UNUSED, c_nothrow_p b UNUSED)
   { return NULL; }
 void _ZdaPvRKSt9nothrow_t (void * a UNUSED, c_nothrow_p b UNUSED) { return; }
-
+#endif
 #endif
Index: gcc/config/i386/darwin.h
===================================================================
--- gcc/config/i386/darwin.h	(revision 195764)
+++ gcc/config/i386/darwin.h	(working copy)
@@ -131,8 +131,7 @@ extern int darwin_emit_branch_islands;
   "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
    %{mpc32:crtprec32.o%s} \
    %{mpc64:crtprec64.o%s} \
-   %{mpc80:crtprec80.o%s} \
-   %{fgnu-tm: -lcrttme.o}"
+   %{mpc80:crtprec80.o%s}" TM_DESTRUCTOR
 
 #undef SUBTARGET_EXTRA_SPECS
 #define SUBTARGET_EXTRA_SPECS                                   \
Index: gcc/config/darwin.h
===================================================================
--- gcc/config/darwin.h	(revision 195764)
+++ gcc/config/darwin.h	(working copy)
@@ -363,7 +363,8 @@ extern GTY(()) int darwin_ms_struct;
   %{shared-libgcc:%:version-compare(< 10.5 mmacosx-version-min= crt3.o%s)}"
 
 /* We want a destructor last in the list.  */
-#define ENDFILE_SPEC "%{fgnu-tm: -lcrttme.o}"
+#define TM_DESTRUCTOR "%{fgnu-tm: -lcrttme.o}"
+#define ENDFILE_SPEC TM_DESTRUCTOR
 
 #define DARWIN_EXTRA_SPECS						\
   { "darwin_crt1", DARWIN_CRT1_SPEC },					\
Index: libitm/alloc_cpp.cc
===================================================================
--- libitm/alloc_cpp.cc	(revision 195861)
+++ libitm/alloc_cpp.cc	(working copy)
@@ -60,7 +60,7 @@
 extern void *_ZnaXRKSt9nothrow_t (size_t, c_nothrow_p) __attribute__((weak));
 extern void _ZdaPvRKSt9nothrow_t (void *, c_nothrow_p) __attribute__((weak));
 
-#if !defined (HAVE_ELF_STYLE_WEAKREF) && !defined (__MACH__)
+#if !defined (HAVE_ELF_STYLE_WEAKREF) 
 void *_ZnwX (size_t) { return NULL; }
 void _ZdlPv (void *) { return; }
 void *_ZnaX (size_t) { return NULL; }
Index: libitm/eh_cpp.cc
===================================================================
--- libitm/eh_cpp.cc	(revision 195861)
+++ libitm/eh_cpp.cc	(working copy)
@@ -39,7 +39,7 @@
 extern void __cxa_end_catch (void) WEAK;
 extern void __cxa_tm_cleanup (void *, void *, unsigned int) WEAK;
 
-#if !defined (HAVE_ELF_STYLE_WEAKREF) && !defined (__MACH__)
+#if !defined (HAVE_ELF_STYLE_WEAKREF) 
 void *__cxa_allocate_exception (size_t) { return NULL; }
 void __cxa_throw (void *, void *, void *) { return; }
 void *__cxa_begin_catch (void *) { return NULL; }