diff --git a/gcc/testsuite/gcc.dg/addr_equal-1.c b/gcc/testsuite/gcc.dg/addr_equal-1.c
index 35fa0102e3063..db65dea4a8d2a 100644
--- a/gcc/testsuite/gcc.dg/addr_equal-1.c
+++ b/gcc/testsuite/gcc.dg/addr_equal-1.c
@@ -1,9 +1,8 @@
-/* { dg-do run { target { nonpic || pie_enabled } } } */
-/* { dg-require-weak "" } */
+/* { dg-do run { target { { nonpic || pie_enabled } && weak_undefined } } } */
 /* { dg-require-alias "" } */
 /* { dg-options "-O2 -fdelete-null-pointer-checks" } */
-/* { dg-skip-if "" { powerpc-ibm-aix* } } */
 /* { dg-skip-if "function pointers can be NULL" { keeps_null_pointer_checks } } */
+/* { dg-add-options weak_undefined } */
 void abort (void);
 extern int undef_var0, undef_var1;
 extern __attribute__ ((weak)) int weak_undef_var0;
diff --git a/gcc/testsuite/gcc.dg/torture/pr53922.c b/gcc/testsuite/gcc.dg/torture/pr53922.c
index b3f2c1a58f830..07359d6764964 100644
--- a/gcc/testsuite/gcc.dg/torture/pr53922.c
+++ b/gcc/testsuite/gcc.dg/torture/pr53922.c
@@ -1,11 +1,5 @@
-/* { dg-do run } */
-/* { dg-require-weak "" } */
-/* { dg-skip-if "No undefined" { *-*-mingw* } } */
-/* { dg-skip-if "No undefined weak" { *-*-aix* } } */
-/* { dg-skip-if "No undefined weak" { hppa*-*-hpux* && { ! lp64 } } } */
-/* { dg-skip-if "No undefined weak" { nvptx-*-* } } */
-/* { dg-options "-Wl,-undefined,dynamic_lookup" { target *-*-darwin* } } */
-/* { dg-additional-options "-Wl,-flat_namespace" { target *-*-darwin[89]* } } */
+/* { dg-do run { target { weak_undefined } } } */
+/* { dg-add-options weak_undefined } */
 
 int x(int a)
 {
diff --git a/gcc/testsuite/gcc.dg/torture/pr60092.c b/gcc/testsuite/gcc.dg/torture/pr60092.c
index 74e7c174a8323..102ba6e0d9f87 100644
--- a/gcc/testsuite/gcc.dg/torture/pr60092.c
+++ b/gcc/testsuite/gcc.dg/torture/pr60092.c
@@ -1,12 +1,7 @@
-/* { dg-do run } */
-/* { dg-require-weak "" } */
-/* { dg-skip-if "No undefined weak" { hppa*-*-hpux* && { ! lp64 } } } */
-/* { dg-skip-if "No undefined weak" { nvptx-*-* } } */
-/* { dg-additional-options "-Wl,-undefined,dynamic_lookup" { target *-*-darwin* } } */
-/* { dg-additional-options "-Wl,-flat_namespace" { target *-*-darwin[89]* } } */
+/* { dg-do run { target { posix_memalign } } } */
 
 typedef __SIZE_TYPE__ size_t;
-extern int posix_memalign(void **memptr, size_t alignment, size_t size) __attribute__((weak));
+extern int posix_memalign(void **memptr, size_t alignment, size_t size);
 extern void abort(void);
 int
 main (void)
@@ -14,9 +9,6 @@ main (void)
   void *p;
   int ret;
 
-  if (!posix_memalign)
-    return 0;
-
   p = (void *)&ret;
   ret = posix_memalign (&p, sizeof (void *), -1);
   if (p != (void *)&ret)
diff --git a/gcc/testsuite/gcc.dg/torture/pr90020.c b/gcc/testsuite/gcc.dg/torture/pr90020.c
index 657c4ccfe45c4..40035aa758e6e 100644
--- a/gcc/testsuite/gcc.dg/torture/pr90020.c
+++ b/gcc/testsuite/gcc.dg/torture/pr90020.c
@@ -1,8 +1,5 @@
-/* { dg-do run } */
-/* { dg-skip-if "No undefined weak" { hppa*-*-hpux* || powerpc-ibm-aix* } } */
-/* { dg-require-weak "" } */
-/* { dg-additional-options "-Wl,-undefined,dynamic_lookup" { target *-*-darwin* } } */
-/* { dg-additional-options "-Wl,-flat_namespace" { target *-*-darwin[89]* } } */
+/* { dg-do run  { target { weak_undefined } } } */
+/* { dg-add-options weak_undefined } */
 
 void __attribute__((noinline,noclone))
 check (int i)
diff --git a/gcc/testsuite/gcc.dg/vect/vect-tail-nomask-1.c b/gcc/testsuite/gcc.dg/vect/vect-tail-nomask-1.c
index e5bbeaede095b..ee9ab2e9d910b 100644
--- a/gcc/testsuite/gcc.dg/vect/vect-tail-nomask-1.c
+++ b/gcc/testsuite/gcc.dg/vect/vect-tail-nomask-1.c
@@ -1,14 +1,10 @@
-/* { dg-require-weak "" } */
-/* { dg-skip-if "No undefined weak" { hppa*-*-hpux* && { ! lp64 } } } */
-/* { dg-skip-if "No undefined weak" { nvptx-*-* } } */
-/* { dg-additional-options "-Wl,-undefined,dynamic_lookup" { target *-*-darwin* } } */
-/* { dg-additional-options "-Wl,-flat_namespace" { target *-*-darwin[89]* } } */
+/* { dg-skip-if "No undefined weak" { ! { posix_memalign } } } */
 /* { dg-additional-options "--param vect-epilogues-nomask=1 -mavx2" { target avx2_runtime } } */
 
 #define SIZE 1023
 #define ALIGN 64
 
-extern int posix_memalign(void **memptr, __SIZE_TYPE__ alignment, __SIZE_TYPE__ size) __attribute__((weak));
+extern int posix_memalign(void **memptr, __SIZE_TYPE__ alignment, __SIZE_TYPE__ size);
 extern void free (void *);
 
 void __attribute__((noinline))
@@ -98,9 +94,6 @@ run_test ()
 int
 main (int argc, const char **argv)
 {
-  if (!posix_memalign)
-    return 0;
-
   run_test ();
   return 0;
 }
diff --git a/gcc/testsuite/gcc.target/aarch64/aapcs64/aapcs64.exp b/gcc/testsuite/gcc.target/aarch64/aapcs64/aapcs64.exp
index 8cf9cc1e8e585..ef3799fdee390 100644
--- a/gcc/testsuite/gcc.target/aarch64/aapcs64/aapcs64.exp
+++ b/gcc/testsuite/gcc.target/aarch64/aapcs64/aapcs64.exp
@@ -32,12 +32,15 @@ set additional_flags "-W -Wall -Wno-abi -fno-pie -no-pie"
 # Test parameter passing.  This uses abitest.S which relies on weak
 # symbols.
 
-if { [check_weak_available] } {
+set additional_flags_for_abitest $additional_flags
+lappend additional_flags_for_abitest [add_options_for_weak_undefined ""]
+
+if { [check_effective_target_weak_undefined] } {
     foreach src [lsort [glob -nocomplain $srcdir/$subdir/test_*.c]] {
 	if {[runtest_file_p $runtests $src]} {
 	    c-torture-execute [list $src \
 				    $srcdir/$subdir/abitest.S] \
-				    $additional_flags
+		$additional_flags_for_abitest
 	}
     }
 }
@@ -54,28 +57,28 @@ foreach src [lsort [glob -nocomplain $srcdir/$subdir/rec_*.c]] {
 
 # Test unnamed argument retrieval via the va_arg macro.  This uses abitest.S
 # which relies on weak symbols.
-if { [check_weak_available] } {
+if { [check_effective_target_weak_undefined] } {
     foreach src [lsort [glob -nocomplain $srcdir/$subdir/va_arg-*.c]] {
 	if {[runtest_file_p $runtests $src]} {
 	    c-torture-execute [list $src \
 				    $srcdir/$subdir/abitest.S] \
-				    $additional_flags
+		$additional_flags_for_abitest
 	}
     }
 }
 
 # Test function return value.  This uses abitest.S which relies on
 # weak symbols.
-if { [check_weak_available] } {
+if { [check_effective_target_weak_undefined] } {
     #   Disable -fipa-ra to prevent the compiler from generating
     #   conflicting code.
-    set additional_flags_for_func_ret $additional_flags
+    set additional_flags_for_func_ret $additional_flags_for_abitest
     append additional_flags_for_func_ret " -fno-ipa-ra"
     foreach src [lsort [glob -nocomplain $srcdir/$subdir/func-ret-*.c]] {
 	if {[runtest_file_p $runtests $src]} {
 	    c-torture-execute [list $src \
 				    $srcdir/$subdir/abitest.S] \
-				    $additional_flags_for_func_ret
+		$additional_flags_for_func_ret
 	}
     }
 }
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index fcfe290d07d71..ac6f000afd18e 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -356,6 +356,18 @@ proc check_weak_available { } {
     }
 }
 
+# return options to add to enable weak undefined symbols.
+
+proc add_options_for_weak_undefined { flags } {
+    if { [istarget *-*-darwin*] } {
+	lappend flags "-Wl,-undefined,dynamic_lookup"
+	if { [istarget *-*-darwin[89]*] } {
+	    lappend flags "-Wl,-flat_namespace"
+	}
+    }
+    return $flags
+}
+
 # return 1 if weak undefined symbols are supported.
 
 proc check_effective_target_weak_undefined { } {
@@ -365,7 +377,7 @@ proc check_effective_target_weak_undefined { } {
     return [check_runtime weak_undefined {
 	extern void foo () __attribute__((weak));
 	int main (void) { if (foo) return 1; return 0; }
-    } ""]
+    } [add_options_for_weak_undefined ""]]
 }
 
 ###############################
@@ -1154,6 +1166,16 @@ proc check_effective_target_clone {} {
     return [check_function_available "clone"]
 }
 
+# Return 1 if the target supports posix_memalign, 0 otherwise.
+proc check_effective_target_posix_memalign {} {
+    if { [istarget *-*-vxworks*] } {
+	# VxWorks doesn't have posix_memalign but our way to test
+	# can't tell as we're doing partial links for kernel modules.
+	return 0
+     }    
+    return [check_function_available "posix_memalign"]
+}
+
 # Return 1 if the target supports setrlimit, 0 otherwise.
 proc check_effective_target_setrlimit {} {
     # Darwin has non-posix compliant RLIMIT_AS
@@ -10827,7 +10849,7 @@ proc check_vect_support_and_set_flags { } {
         } else {
             set dg-do-what-default link
         }
-    } elseif [istarget "aarch64*-*-*"] {
+    } elseif [istarget aarch64*-*-*] {
         set dg-do-what-default run
     } elseif [istarget s390*-*-*] {
 	# The S/390 backend set a default of 2 for that value.
