Index: cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- cmake/modules/HandleLLVMOptions.cmake
+++ cmake/modules/HandleLLVMOptions.cmake
@@ -145,6 +145,7 @@
 # Pass -Wl,-z,defs. This makes sure all symbols are defined. Otherwise a DSO
 # build might work on ELF but fail on MachO/COFF.
 if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin" OR WIN32 OR CYGWIN OR
+        ${CMAKE_SYSTEM_NAME} MATCHES "DragonFly" OR
         ${CMAKE_SYSTEM_NAME} MATCHES "FreeBSD" OR
         ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD") AND
    NOT LLVM_USE_SANITIZER)