diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0012dcbadc5..f855ed05b12 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2006-02-19  Roger Sayle  <roger@eyesopen.com>
+
+	* gthr-posix.h: On Tru64, map __gthr_foo as a weak reference to
+	__foo and not foo when _PTHREAD_USE_MANGLED_NAMES_ is defined.
+
 2006-02-19  David Edelsohn  <edelsohn@gnu.org>
 
 	* config/rs6000/xcoff.h (TARGET_ASM_OUTPUT_ANCHOR): Define.
diff --git a/gcc/gthr-posix.h b/gcc/gthr-posix.h
index 38fc3813755..c06e99f0f6d 100644
--- a/gcc/gthr-posix.h
+++ b/gcc/gthr-posix.h
@@ -1,6 +1,6 @@
 /* Threads compatibility routines for libgcc2 and libobjc.  */
 /* Compile this one with gcc.  */
-/* Copyright (C) 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2005
+/* Copyright (C) 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -59,33 +59,61 @@ typedef pthread_mutex_t __gthread_recursive_mutex_t;
 #endif
 
 #if SUPPORTS_WEAK && GTHREAD_USE_WEAK
-# define __gthrw(name) \
-  static __typeof(name) __gthrw_ ## name __attribute__ ((__weakref__(#name)));
+# define __gthrw2(name,name2) \
+  static __typeof(name) __gthrw_ ## name __attribute__ ((__weakref__(#name2)));
 # define __gthrw_(name) __gthrw_ ## name
 #else
-# define __gthrw(name)
+# define __gthrw2(name,name2)
 # define __gthrw_(name) name
 #endif
 
+/* Typically, __gthrw_foo is a weak refernce to symbol foo.  */
+#define __gthrw(name) __gthrw2(name,name)
+
+/* On Tru64, /usr/include/pthread.h uses #pragma extern_prefix "__" to
+   map a subset of the POSIX pthread API to mangled versions of their
+   names.  */
+#if defined(__osf__) && defined(_PTHREAD_USE_MANGLED_NAMES_)
+__gthrw2(pthread_once,__pthread_once)
+__gthrw2(pthread_getspecific,__pthread_getspecific)
+__gthrw2(pthread_setspecific,__pthread_setspecific)
+__gthrw2(pthread_create,__pthread_create)
+__gthrw2(pthread_cancel,__pthread_cancel)
+__gthrw2(pthread_mutex_lock,__pthread_mutex_lock)
+__gthrw2(pthread_mutex_trylock,__pthread_mutex_trylock)
+__gthrw2(pthread_mutex_unlock,__pthread_mutex_unlock)
+__gthrw2(pthread_mutex_init,__pthread_mutex_init)
+#else
 __gthrw(pthread_once)
-__gthrw(pthread_key_create)
-__gthrw(pthread_key_delete)
 __gthrw(pthread_getspecific)
 __gthrw(pthread_setspecific)
 __gthrw(pthread_create)
 __gthrw(pthread_cancel)
-
 __gthrw(pthread_mutex_lock)
 __gthrw(pthread_mutex_trylock)
 __gthrw(pthread_mutex_unlock)
+__gthrw(pthread_mutex_init)
+#endif
+
+__gthrw(pthread_key_create)
+__gthrw(pthread_key_delete)
 __gthrw(pthread_mutexattr_init)
 __gthrw(pthread_mutexattr_settype)
 __gthrw(pthread_mutexattr_destroy)
 
-__gthrw(pthread_mutex_init)
 
 #if defined(_LIBOBJC) || defined(_LIBOBJC_WEAK)
 /* Objective-C.  */
+#if defined(__osf__) && defined(_PTHREAD_USE_MANGLED_NAMES_)
+__gthrw2(pthread_cond_broadcast,__pthread_cond_broadcast)
+__gthrw2(pthread_cond_destroy,__pthread_cond_destroy)
+__gthrw2(pthread_cond_init,__pthread_cond_init)
+__gthrw2(pthread_cond_signal,__pthread_cond_signal)
+__gthrw2(pthread_cond_wait,__pthread_cond_wait)
+__gthrw2(pthread_exit,__pthread_exit)
+__gthrw2(pthread_mutex_destroy,__pthread_mutex_destroy)
+__gthrw2(pthread_self,__pthread_self)
+#else
 __gthrw(pthread_cond_broadcast)
 __gthrw(pthread_cond_destroy)
 __gthrw(pthread_cond_init)
@@ -94,6 +122,7 @@ __gthrw(pthread_cond_wait)
 __gthrw(pthread_exit)
 __gthrw(pthread_mutex_destroy)
 __gthrw(pthread_self)
+#endif /* __osf__ && _PTHREAD_USE_MANGLED_NAMES_ */
 #ifdef _POSIX_PRIORITY_SCHEDULING
 #ifdef _POSIX_THREAD_PRIORITY_SCHEDULING
 __gthrw(sched_get_priority_max)