Index: b/usr/src/head/search.h
===================================================================
--- a/usr/src/head/search.h
+++ b/usr/src/head/search.h
@@ -32,7 +32,7 @@
 #ifndef _SEARCH_H
 #define	_SEARCH_H
 
-#include <sys/feature_tests.h>
+#include <features.h>
 #include <sys/types.h>
 
 #ifdef	__cplusplus
@@ -69,6 +69,10 @@ void *tfind(const void *, void *const *,
 void *tsearch(const void *, void **, int (*)(const void *, const void *));
 void twalk(const void *, void (*)(const void *, VISIT, int));
 
+#if defined(__EXTENSIONS__) || defined(_GNU_SOURCE)
+extern void tdestroy(void *root, void (*)(void *));
+#endif
+
 
 #if defined(__EXTENSIONS__) || !defined(_XOPEN_SOURCE)
 /* BSEARCH(3C) */
Index: b/usr/src/lib/libc/port/mapfile-vers
===================================================================
--- a/usr/src/lib/libc/port/mapfile-vers
+++ b/usr/src/lib/libc/port/mapfile-vers
@@ -280,6 +280,7 @@ SYMBOL_VERSION DYSON_1 {
         program_invocation_name;
         program_invocation_short_name;
         rawmemchr;
+        tdestroy;
         wmempcpy;
 } ILLUMOS_0.3;
 
Index: b/usr/src/lib/libc/port/gen/tsearch.c
===================================================================
--- a/usr/src/lib/libc/port/gen/tsearch.c
+++ b/usr/src/lib/libc/port/gen/tsearch.c
@@ -156,3 +156,23 @@ __twalk(NODE *root,		/* Root of the tree
 		(*action)(root, endorder, level);
 	}
 }
+
+
+static void
+tdestroy_recursive(NODE *r, void (*free_node)(void *nodep))
+{
+    if (NULL != r->llink)
+        tdestroy_recursive(r->llink, free_node);
+    if (NULL != r->rlink)
+        tdestroy_recursive(r->rlink, free_node);
+    (*free_node) ((void*) r->key);
+    lfree(r, sizeof (NODE));
+}
+
+void tdestroy(void *root, void (*free_node)(void *nodep))
+{
+    NODE *r = (NODE*) root;
+    if (NULL != r)
+        tdestroy_recursive(r, free_node);
+}
+