diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -235,6 +235,10 @@
 def clang_ignored_m_Group : OptionGroup<"<clang ignored m group>">,
   Group<m_Group>, Flags<[Ignored]>;
 
+// Unsupported flang groups
+def flang_ignored_w_Group : OptionGroup<"<flang ignored W group>">,
+  Group<W_Group>, Flags<[FlangOnlyOption, Ignored]>;
+
 // Group for clang options in the process of deprecation.
 // Please include the version that deprecated the flag as comment to allow
 // easier garbage collection.
@@ -4874,6 +4878,10 @@
   def fno_#NAME : Flag<["-"], "fno-"#name>;
 }
 
+multiclass FlangIgnoredWarning<string name> {
+  def unsupported_warning_w#NAME : Flag<["-", "--"], "W"#name>, Group<flang_ignored_w_Group>;
+}
+
 defm : BooleanFFlag<"keep-inline-functions">, Group<clang_ignored_gcc_optimization_f_Group>;
 
 def fprofile_dir : Joined<["-"], "fprofile-dir=">, Group<f_Group>;
@@ -5034,6 +5042,34 @@
 defm underscoring : BooleanFFlag<"underscoring">, Group<gfortran_Group>;
 defm whole_file : BooleanFFlag<"whole-file">, Group<gfortran_Group>;
 
+//
+defm : FlangIgnoredWarning<"extra">;
+defm : FlangIgnoredWarning<"aliasing">;
+defm : FlangIgnoredWarning<"ampersand">;
+defm : FlangIgnoredWarning<"array-bounds">;
+defm : FlangIgnoredWarning<"c-binding-type">;
+defm : FlangIgnoredWarning<"character-truncation">;
+defm : FlangIgnoredWarning<"conversion">;
+defm : FlangIgnoredWarning<"do-subscript">;
+defm : FlangIgnoredWarning<"function-elimination">;
+defm : FlangIgnoredWarning<"implicit-interface">;
+defm : FlangIgnoredWarning<"implicit-procedure">;
+defm : FlangIgnoredWarning<"intrinsic-shadow">;
+defm : FlangIgnoredWarning<"use-without-only">;
+defm : FlangIgnoredWarning<"intrinsics-std">;
+defm : FlangIgnoredWarning<"line-truncation">;
+defm : FlangIgnoredWarning<"no-align-commons">;
+defm : FlangIgnoredWarning<"no-overwrite-recursive">;
+defm : FlangIgnoredWarning<"no-tabs">;
+defm : FlangIgnoredWarning<"real-q-constant">;
+defm : FlangIgnoredWarning<"surprising">;
+defm : FlangIgnoredWarning<"underflow">;
+defm : FlangIgnoredWarning<"unused-parameter">;
+defm : FlangIgnoredWarning<"realloc-lhs">;
+defm : FlangIgnoredWarning<"realloc-lhs-all">;
+defm : FlangIgnoredWarning<"frontend-loop-interchange">;
+defm : FlangIgnoredWarning<"target-lifetime">;
+
 // C++ SYCL options
 def fsycl : Flag<["-"], "fsycl">, Flags<[NoXarchOption, CoreOption]>,
   Group<sycl_Group>, HelpText<"Enables SYCL kernels compilation for device">;
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -604,14 +604,17 @@
   // TODO: Currently throws a Diagnostic for anything other than -W<error>,
   // this has to change when other -W<opt>'s are supported.
   if (args.hasArg(clang::driver::options::OPT_W_Joined)) {
-    if (args.getLastArgValue(clang::driver::options::OPT_W_Joined)
-            .equals("error")) {
-      res.setWarnAsErr(true);
-    } else {
-      const unsigned diagID =
-          diags.getCustomDiagID(clang::DiagnosticsEngine::Error,
-                                "Only `-Werror` is supported currently.");
-      diags.Report(diagID);
+    const auto &wArgs =
+        args.getAllArgValues(clang::driver::options::OPT_W_Joined);
+    for (const auto &wArg : wArgs) {
+      if (wArg == "error") {
+        res.setWarnAsErr(true);
+      } else {
+        const unsigned diagID =
+            diags.getCustomDiagID(clang::DiagnosticsEngine::Error,
+                                  "Only `-Werror` is supported currently.");
+        diags.Report(diagID);
+      }
     }
   }
 
diff --git a/flang/test/Driver/werror-all.f90 b/flang/test/Driver/werror-all.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Driver/werror-all.f90
@@ -0,0 +1,13 @@
+! Ensures that -Werror is read regardless of whether or not other -W
+! flags are present in the CLI args
+
+! RUN: not %flang -std=f2018 -Werror -Wextra %s 2>&1 | FileCheck %s --check-prefix=WRONG 
+! RUN: %flang -std=f2018 -Wextra -Wall %s 2>&1 | FileCheck %s --check-prefix=CHECK-OK
+
+! WRONG: Semantic errors in
+! CHECK-OK: FORALL index variable
+
+program werror_check_all
+  integer :: a(3)
+  forall (j=1:n) a(i) = 1
+end program werror_check_all
diff --git a/flang/test/Driver/wextra-ok.f90 b/flang/test/Driver/wextra-ok.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Driver/wextra-ok.f90
@@ -0,0 +1,11 @@
+! Ensure that supplying -Wextra into flang-new does not raise error
+! The first check should be changed if -Wextra is implemented
+
+! RUN: %flang -std=f2018 -Wextra %s 2>&1 | FileCheck %s --check-prefix=CHECK-OK
+! RUN: not %flang -std=f2018 -Wblah -Wextra %s 2>&1 | FileCheck %s --check-prefix=WRONG
+
+! CHECK-OK: argument unused during compilation: '-Wextra'
+! WRONG: Only `-Werror` is supported currently.
+
+program wextra_ok
+end program wextra_ok