diff --git a/compiler-rt/cmake/Modules/AddCompilerRT.cmake b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
index 42ae7ad1ecd5..c2863d5f2f8c 100644
--- a/compiler-rt/cmake/Modules/AddCompilerRT.cmake
+++ b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
@@ -256,6 +256,7 @@ set(COMPILER_RT_GTEST_CFLAGS
 )
 
 append_list_if(COMPILER_RT_DEBUG -DSANITIZER_DEBUG=1 COMPILER_RT_UNITTEST_CFLAGS)
+append_list_if(COMPILER_RT_HAS_WCOVERED_SWITCH_DEFAULT_FLAG -Wno-covered-switch-default COMPILER_RT_UNITTEST_CFLAGS)
 
 if(MSVC)
   # clang doesn't support exceptions on Windows yet.
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
index 5e2eefc30e06..7d9aa446be27 100644
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -57,6 +57,7 @@ check_cxx_compiler_flag("-Werror -Wgnu"                COMPILER_RT_HAS_WGNU_FLAG
 check_cxx_compiler_flag("-Werror -Wnon-virtual-dtor"   COMPILER_RT_HAS_WNON_VIRTUAL_DTOR_FLAG)
 check_cxx_compiler_flag("-Werror -Wvariadic-macros"    COMPILER_RT_HAS_WVARIADIC_MACROS_FLAG)
 check_cxx_compiler_flag("-Werror -Wunused-parameter"   COMPILER_RT_HAS_WUNUSED_PARAMETER_FLAG)
+check_cxx_compiler_flag("-Werror -Wcovered-switch-default" COMPILER_RT_HAS_WCOVERED_SWITCH_DEFAULT_FLAG)
 
 check_cxx_compiler_flag(/W4 COMPILER_RT_HAS_W4_FLAG)
 check_cxx_compiler_flag(/WX COMPILER_RT_HAS_WX_FLAG)