diff --git a/libcxx/test/std/containers/sequences/array/array.creation/to_array.fail.cpp b/libcxx/test/std/containers/sequences/array/array.creation/to_array.fail.cpp
index 39b92a0468dc..49ad6a61037f 100644
--- a/libcxx/test/std/containers/sequences/array/array.creation/to_array.fail.cpp
+++ b/libcxx/test/std/containers/sequences/array/array.creation/to_array.fail.cpp
@@ -14,8 +14,6 @@
 #include "test_macros.h"
 #include "MoveOnly.h"
 
-// expected-warning@array:* 0-1 {{suggest braces around initialization of subobject}}
-
 int main(int, char**) {
   {
     char source[3][6] = {"hi", "world"};
diff --git a/libcxx/utils/libcxx/test/config.py b/libcxx/utils/libcxx/test/config.py
index 2f8dc4f80b59..ce77ec8c71c9 100644
--- a/libcxx/utils/libcxx/test/config.py
+++ b/libcxx/utils/libcxx/test/config.py
@@ -829,7 +829,7 @@ def configure_warnings(self):
         self.cxx.useWarnings(enable_warnings)
         self.cxx.warning_flags += [
             '-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER',
-            '-Wall', '-Wextra'
+            '-Wall', '-Wextra', '-Werror'
         ]
         if self.cxx.hasWarningFlag('-Wuser-defined-warnings'):
             self.cxx.warning_flags += ['-Wuser-defined-warnings']
@@ -849,7 +849,11 @@ def configure_warnings(self):
         self.cxx.addWarningFlagIfSupported('-Wunused-variable')
         self.cxx.addWarningFlagIfSupported('-Wunused-parameter')
         self.cxx.addWarningFlagIfSupported('-Wunreachable-code')
-        self.cxx.addWarningFlagIfSupported('-Wno-unused-local-typedef')
+        std = self.get_lit_conf('std', None)
+        if std in ['c++98', 'c++03']:
+            # The '#define static_assert' provided by libc++ in C++03 mode
+            # causes an unused local typedef whenever it is used.
+            self.cxx.addWarningFlagIfSupported('-Wno-unused-local-typedef')
 
     def configure_sanitizer(self):
         san = self.get_lit_conf('use_sanitizer', '').strip()
@@ -978,9 +982,8 @@ def configure_substitutions(self):
         sub.append(('%{libcxx_src_root}', self.libcxx_src_root))
         # Configure flags substitutions
         flags = self.cxx.flags + (self.cxx.modules_flags if self.cxx.use_modules else [])
-        compile_flags = self.cxx.compile_flags + self.cxx.warning_flags
         sub.append(('%{flags}',         ' '.join(map(pipes.quote, flags))))
-        sub.append(('%{compile_flags}', ' '.join(map(pipes.quote, compile_flags))))
+        sub.append(('%{compile_flags}', ' '.join(map(pipes.quote, self.cxx.compile_flags))))
         sub.append(('%{link_flags}',    ' '.join(map(pipes.quote, self.cxx.link_flags))))
         sub.append(('%{link_libcxxabi}', pipes.quote(self.cxx.link_libcxxabi_flag)))
 
diff --git a/libcxx/utils/libcxx/test/newformat.py b/libcxx/utils/libcxx/test/newformat.py
index 31720ac9f2e8..f704b968b6da 100644
--- a/libcxx/utils/libcxx/test/newformat.py
+++ b/libcxx/utils/libcxx/test/newformat.py
@@ -173,37 +173,33 @@ def execute(self, test, litConfig):
         if '-fmodules' in test.config.available_features and self._disableWithModules(test, litConfig):
             return lit.Test.Result(lit.Test.UNSUPPORTED, 'Test {} is unsupported when modules are enabled')
 
-        # TODO(ldionne): Enable -Werror with all supported compilers.
-        clangOrAppleClang = {'clang', 'apple-clang'}.intersection(test.config.available_features) != set()
-        werror = '-Werror' if clangOrAppleClang else ''
-
         if re.search('[.]sh[.][^.]+$', filename):
             steps = [ ] # The steps are already in the script
             return self._executeShTest(test, litConfig, steps)
         elif filename.endswith('.compile.pass.cpp'):
             steps = [
-                "%dbg(COMPILED WITH) %{{cxx}} %s {} %{{flags}} %{{compile_flags}} -fsyntax-only".format(werror)
+                "%dbg(COMPILED WITH) %{cxx} %s %{flags} %{compile_flags} -fsyntax-only"
             ]
             return self._executeShTest(test, litConfig, steps)
         elif filename.endswith('.compile.fail.cpp'):
             steps = [
-                "%dbg(COMPILED WITH) ! %{{cxx}} %s {} %{{flags}} %{{compile_flags}} -fsyntax-only".format(werror)
+                "%dbg(COMPILED WITH) ! %{cxx} %s %{flags} %{compile_flags} -fsyntax-only"
             ]
             return self._executeShTest(test, litConfig, steps)
         elif filename.endswith('.link.pass.cpp'):
             steps = [
-                "%dbg(COMPILED WITH) %{{cxx}} %s {} %{{flags}} %{{compile_flags}} %{{link_flags}} -o %t.exe".format(werror)
+                "%dbg(COMPILED WITH) %{cxx} %s %{flags} %{compile_flags} %{link_flags} -o %t.exe"
             ]
             return self._executeShTest(test, litConfig, steps)
         elif filename.endswith('.link.fail.cpp'):
             steps = [
-                "%dbg(COMPILED WITH) %{{cxx}} %s {} %{{flags}} %{{compile_flags}} -c -o %t.o".format(werror),
+                "%dbg(COMPILED WITH) %{cxx} %s %{flags} %{compile_flags} -c -o %t.o",
                 "%dbg(LINKED WITH) ! %{cxx} %t.o %{flags} %{link_flags} -o %t.exe"
             ]
             return self._executeShTest(test, litConfig, steps)
         elif filename.endswith('.run.fail.cpp'):
             steps = [
-                "%dbg(COMPILED WITH) %{{cxx}} %s {} %{{flags}} %{{compile_flags}} %{{link_flags}} -o %t.exe".format(werror),
+                "%dbg(COMPILED WITH) %{cxx} %s %{flags} %{compile_flags} %{link_flags} -o %t.exe",
                 "%dbg(EXECUTED AS) %{exec} ! %t.exe"
             ]
             return self._executeShTest(test, litConfig, steps, fileDependencies=['%t.exe'])
@@ -216,7 +212,7 @@ def execute(self, test, litConfig):
         # suffixes above too.
         elif filename.endswith('.pass.cpp') or filename.endswith('.pass.mm'):
             steps = [
-                "%dbg(COMPILED WITH) %{{cxx}} %s {} %{{flags}} %{{compile_flags}} %{{link_flags}} -o %t.exe".format(werror),
+                "%dbg(COMPILED WITH) %{cxx} %s %{flags} %{compile_flags} %{link_flags} -o %t.exe",
                 "%dbg(EXECUTED AS) %{exec} %t.exe"
             ]
             return self._executeShTest(test, litConfig, steps, fileDependencies=['%t.exe'])
@@ -230,7 +226,7 @@ def execute(self, test, litConfig):
                 ]
             else:
                 steps = [
-                    "%dbg(COMPILED WITH) ! %{{cxx}} {} %s %{{flags}} %{{compile_flags}} -fsyntax-only".format(werror)
+                    "%dbg(COMPILED WITH) ! %{cxx} %s %{flags} %{compile_flags} -fsyntax-only"
                 ]
             return self._executeShTest(test, litConfig, steps)
         else: