diff --git a/cmake/find_cxx.cmake b/cmake/find_cxx.cmake
index 35a0b9d0927..da6e3d48cab 100644
--- a/cmake/find_cxx.cmake
+++ b/cmake/find_cxx.cmake
@@ -1,5 +1,5 @@
 if (OS_LINUX AND COMPILER_CLANG)
-    option (USE_LIBCXX "Use libc++ and libc++abi instead of libstdc++" ${HAVE_LIBCXX})
+    option (USE_LIBCXX "Use libc++ and libc++abi instead of libstdc++" ON)
     option (USE_INTERNAL_LIBCXX_LIBRARY "Set to FALSE to use system libcxx and libcxxabi libraries instead of bundled" ${NOT_UNBUNDLED})
 endif()
 
diff --git a/contrib/capnproto-cmake/CMakeLists.txt b/contrib/capnproto-cmake/CMakeLists.txt
index 275007c145f..d92a5a282ce 100644
--- a/contrib/capnproto-cmake/CMakeLists.txt
+++ b/contrib/capnproto-cmake/CMakeLists.txt
@@ -28,7 +28,8 @@ set (KJ_SRCS
 )
 
 add_library(kj ${KJ_SRCS})
-target_include_directories(kj INTERFACE ${CAPNPROTO_SOURCE_DIR})
+target_include_directories(kj PUBLIC ${CAPNPROTO_SOURCE_DIR})
+target_compile_options(kj PUBLIC -Wno-non-virtual-dtor)
 
 set (CAPNP_SRCS
     ${CAPNPROTO_SOURCE_DIR}/capnp/c++.capnp.c++
diff --git a/contrib/libcxx-cmake/CMakeLists.txt b/contrib/libcxx-cmake/CMakeLists.txt
index 07fa70b9869..e74b4a8364f 100644
--- a/contrib/libcxx-cmake/CMakeLists.txt
+++ b/contrib/libcxx-cmake/CMakeLists.txt
@@ -40,9 +40,9 @@ ${LIBCXX_SOURCE_DIR}/src/random.cpp
 
 add_library(cxx ${SRCS})
 
-target_include_directories(cxx SYSTEM BEFORE PUBLIC $<BUILD_INTERFACE:${LIBCXX_SOURCE_DIR}/include>)
+target_include_directories(cxx BEFORE PUBLIC $<BUILD_INTERFACE:${LIBCXX_SOURCE_DIR}/include>)
 target_compile_definitions(cxx PRIVATE -D_LIBCPP_BUILDING_LIBRARY -DLIBCXX_BUILDING_LIBCXXABI)
-target_compile_options(cxx PRIVATE -nostdinc++)
+target_compile_options(cxx PUBLIC -nostdinc++)
 target_link_libraries(cxx PUBLIC cxxabi)
 
 install(
diff --git a/contrib/libcxxabi-cmake/CMakeLists.txt b/contrib/libcxxabi-cmake/CMakeLists.txt
index 546d39933af..4996c4f2d7b 100644
--- a/contrib/libcxxabi-cmake/CMakeLists.txt
+++ b/contrib/libcxxabi-cmake/CMakeLists.txt
@@ -29,7 +29,7 @@ target_include_directories(cxxabi SYSTEM BEFORE
     PRIVATE $<BUILD_INTERFACE:${LIBCXXABI_SOURCE_DIR}/../libcxx/include>
 )
 target_compile_definitions(cxxabi PRIVATE -D_LIBCPP_BUILDING_LIBRARY)
-target_compile_options(cxxabi PRIVATE -nostdinc++ -fno-sanitize=undefined) # If we don't disable UBSan, infinite recursion happens in dynamic_cast.
+target_compile_options(cxxabi PRIVATE -nostdinc++ -fno-sanitize=undefined -Wno-macro-redefined) # If we don't disable UBSan, infinite recursion happens in dynamic_cast.
 
 if (USE_UNWIND)
     target_link_libraries(cxxabi PRIVATE ${UNWIND_LIBRARIES})