diff --git a/libcxxabi/src/CMakeLists.txt b/libcxxabi/src/CMakeLists.txt
--- a/libcxxabi/src/CMakeLists.txt
+++ b/libcxxabi/src/CMakeLists.txt
@@ -59,6 +59,11 @@
 # Some files depend on libc++ internals.
 include_directories("${LIBCXXABI_LIBCXX_PATH}/src")
 
+# Disable libstdc++/libc++ assertions, even in an LLVM_ENABLE_ASSERTIONS build,
+# to avoid an unwanted dependency on libstdc++/libc++.so.
+add_definitions(-U_GLIBCXX_ASSERTIONS)
+add_definitions(-U_LIBCPP_ENABLE_ASSERTIONS)
+
 if (LIBCXXABI_HAS_CXA_THREAD_ATEXIT_IMPL)
   add_definitions(-DHAVE___CXA_THREAD_ATEXIT_IMPL)
 endif()