diff --git a/src/cmd/builtin/Mamfile b/src/cmd/builtin/Mamfile
index 873ad99d04fc..20f5e7a2a093 100644
--- a/src/cmd/builtin/Mamfile
+++ b/src/cmd/builtin/Mamfile
@@ -37,7 +37,7 @@ make install
 					meta FEATURE/pty features/%>FEATURE/% features/pty pty
 					make features/pty
 					done features/pty
-					exec - iffe ${IFFEFLAGS} -v -c "${CC} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${CCFLAGS} ${LDFLAGS} -lm" ref ${mam_cc_L+-L${INSTALLROOT}/lib} -I${PACKAGE_ast_INCLUDE} -I${INSTALLROOT}/include ${mam_libast} ${mam_libcmd} : run features/pty
+					exec - iffe ${IFFEFLAGS} -v -c "${CC} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${CCFLAGS} ${LDFLAGS}" ref ${mam_cc_L+-L${INSTALLROOT}/lib} -I${PACKAGE_ast_INCLUDE} -I${INSTALLROOT}/include ${mam_libast} ${mam_libcmd} : run features/pty
 				done FEATURE/pty generated
 				make ${PACKAGE_ast_INCLUDE}/ast_time.h implicit
 				done ${PACKAGE_ast_INCLUDE}/ast_time.h
diff --git a/src/cmd/builtin/features/pty b/src/cmd/builtin/features/pty
index 612609b36f21..ab4a041ec530 100755
--- a/src/cmd/builtin/features/pty
+++ b/src/cmd/builtin/features/pty
@@ -13,7 +13,7 @@ lib	openpty,_getpty,ptsname -lutil
 lib	grantpt,unlockpt,posix_openpt stdlib.h
 lib	cfmakeraw termios.h
 
-tst - output{
+tst - -lm output{
 	#include	<fcntl.h>
 	#if _lib_ptsname
 	#include	<stdlib.h>
diff --git a/src/lib/libast/comp/atexit.c b/src/lib/libast/comp/atexit.c
index d0df2d524b3f..c29ce5a73551 100644
--- a/src/lib/libast/comp/atexit.c
+++ b/src/lib/libast/comp/atexit.c
@@ -34,11 +34,7 @@ NoN(atexit)
 
 #else
 
-#if _lib_onexit || _lib_on_exit
-
-#if !_lib_onexit
-#define onexit		on_exit
-#endif
+#if _lib_onexit
 
 extern int		onexit(void(*)(void));
 
diff --git a/src/lib/libast/features/lib b/src/lib/libast/features/lib
index 522c4c3002a1..39410ad93937 100644
--- a/src/lib/libast/features/lib
+++ b/src/lib/libast/features/lib
@@ -29,7 +29,7 @@ lib	getopt,getsubopt,getopt_long,getopt_long_only
 lib	glob,index,iswblank,iswctype,killpg,link,localeconv,madvise
 lib	mbtowc,mbrtowc,memalign,memchr,memcpy,memdup,memmove,memset
 lib	mkdir,mkfifo,mktemp,mktime
-lib	mount,on_exit,onexit,opendir,pathconf
+lib	mount,onexit,opendir,pathconf
 lib	readlink,remove,rename,rewinddir,rindex,rmdir,setlocale
 lib	setpgid,setpgrp,setpgrp2,setreuid,setsid,setuid,sigaction
 lib	sigprocmask,sigsetmask,sigunblock,sigvec,socketpair
diff --git a/src/lib/libast/include/ast.h b/src/lib/libast/include/ast.h
index 00aa5fd805aa..3ce8eccf0b67 100644
--- a/src/lib/libast/include/ast.h
+++ b/src/lib/libast/include/ast.h
@@ -78,6 +78,19 @@ struct _sfio_s;
 #endif
 #endif
 
+/*
+ * tcc on FreeBSD: Avoid using nonexistent math
+ * builtins by pretending to be an ancient gcc.
+ */
+#if __TINYC__ && __GNUC__ >= 3 && __FreeBSD__
+#undef __GNUC__
+#undef __GNUC_MINOR__
+#undef __GNUC_PATCHLEVEL__
+#define __GNUC__ 2
+#define __GNUC_MINOR__ 95
+#define __GNUC_PATCHLEVEL__ 3
+#endif
+
 /*
  * exit() support -- this matches shell exit codes
  */
diff --git a/src/lib/libast/vmalloc/malloc.c b/src/lib/libast/vmalloc/malloc.c
index 8639740dc986..5b3708f21186 100644
--- a/src/lib/libast/vmalloc/malloc.c
+++ b/src/lib/libast/vmalloc/malloc.c
@@ -1040,12 +1040,8 @@ extern Void_t*	F1(_ast_valloc, size_t,n) { return valloc(n); }
 
 #if !_UWIN
 
-#if !_malloc_hook
-
 #include	<malloc.h>
 
-#endif
-
 typedef struct mallinfo Mallinfo_t;
 typedef struct mstats Mstats_t;
 
diff --git a/src/lib/libast/vmalloc/vmexit.c b/src/lib/libast/vmalloc/vmexit.c
index c027fd56ca7b..7752e09676b2 100644
--- a/src/lib/libast/vmalloc/vmexit.c
+++ b/src/lib/libast/vmalloc/vmexit.c
@@ -93,7 +93,7 @@ int	type;
 	return type;
 }
 
-#endif	/* _lib_onexit || _lib_on_exit */
+#endif	/* _lib_onexit */
 
 #endif /*!PACKAGE_ast*/
 
diff --git a/src/lib/libdll/Mamfile b/src/lib/libdll/Mamfile
index 0ef420e967b9..29d9ddb5e82f 100644
--- a/src/lib/libdll/Mamfile
+++ b/src/lib/libdll/Mamfile
@@ -154,7 +154,7 @@ make install
 							done features/dll
 							bind -ldl dontcare
 							bind -last
-							exec - iffe ${IFFEFLAGS} -v -c "${CC} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${CCFLAGS} ${LDFLAGS} -lm" ref ${mam_cc_L+-L.} ${mam_cc_L+-L${INSTALLROOT}/lib} -I${PACKAGE_ast_INCLUDE} -I${INSTALLROOT}/include ${mam_libdl} ${mam_libast} : run features/dll
+							exec - iffe ${IFFEFLAGS} -v -c "${CC} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${CCFLAGS} ${LDFLAGS}" ref ${mam_cc_L+-L.} ${mam_cc_L+-L${INSTALLROOT}/lib} -I${PACKAGE_ast_INCLUDE} -I${INSTALLROOT}/include ${mam_libdl} ${mam_libast} : run features/dll
 						done FEATURE/dll generated
 						exec - cmp 2>/dev/null -s FEATURE/dll dlldefs.h || { rm -f dlldefs.h; silent test -d . || mkdir .; cp FEATURE/dll dlldefs.h; }
 					done dlldefs.h generated
diff --git a/src/lib/libdll/features/dll b/src/lib/libdll/features/dll
index e5d5790f2bd4..86163b46e016 100644
--- a/src/lib/libdll/features/dll
+++ b/src/lib/libdll/features/dll
@@ -74,7 +74,7 @@ tst	run{
 	esac
 	echo "#define _DLL_NEXT_PATH	\"$lib\""
 }end
-tst	- output{
+tst	- -lm output{
 	#include <math.h>
 	#if defined(__MVS__) && !defined(__SUSV3)
 	#define __SUSV3		1