diff --git a/flang-rt/cmake/modules/AddFlangRT.cmake b/flang-rt/cmake/modules/AddFlangRT.cmake
index 58541609829c4..66e54bd2103a3 100644
--- a/flang-rt/cmake/modules/AddFlangRT.cmake
+++ b/flang-rt/cmake/modules/AddFlangRT.cmake
@@ -281,6 +281,7 @@ function (add_flangrt_library name)
 
     # Disable libstdc++/libc++ assertions, even in an LLVM_ENABLE_ASSERTIONS
     # build, to avoid an unwanted dependency on libstdc++/libc++.so.
+    target_compile_definitions(${tgtname} PUBLIC _GLIBCXX_NO_ASSERTIONS)
     if (FLANG_RT_SUPPORTS_UNDEFINE_FLAG)
       target_compile_options(${tgtname} PUBLIC -U_GLIBCXX_ASSERTIONS)
       target_compile_options(${tgtname} PUBLIC -U_LIBCPP_ENABLE_ASSERTIONS)
diff --git a/openmp/runtime/src/CMakeLists.txt b/openmp/runtime/src/CMakeLists.txt
index 08e1753b93636..b22d03d168419 100644
--- a/openmp/runtime/src/CMakeLists.txt
+++ b/openmp/runtime/src/CMakeLists.txt
@@ -167,6 +167,7 @@ endif()
 
 # Disable libstdc++ assertions, even in an LLVM_ENABLE_ASSERTIONS build, to
 # avoid an unwanted dependency on libstdc++.so.
+add_compile_definitions(_GLIBCXX_NO_ASSERTIONS)
 if(NOT WIN32)
   add_definitions(-U_GLIBCXX_ASSERTIONS)
 endif()