diff --git a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
--- a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -124,7 +124,12 @@
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
     endif()
-    set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
+    if (DEFINED LIBCXX_LIT_ARGS)
+      # libc++-specific LIT args always win over generic LIT args
+      set(LLVM_LIT_ARGS "${LIBCXX_LIT_ARGS}")
+    endif()
+    set(LIBCXX_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "libc++-specific options for lit")
+    set(LLVM_LIT_ARGS   "${LIBCXX_LIT_ARGS}"  CACHE STRING "Default options for lit")
   endif()
 
   # Required doc configuration
diff --git a/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake b/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake
--- a/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -124,7 +124,13 @@
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
     endif()
-    set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
+    
+    if (DEFINED LIBCXXABI_LIT_ARGS)
+      # libc++abi-specific LIT args always win over generic LIT args
+      set(LLVM_LIT_ARGS "${LIBCXXABI_LIT_ARGS}")
+    endif()
+    set(LIBCXXABI_LIT_ARGS "${LIT_ARGS_DEFAULT}"   CACHE STRING "libc++abi-specific options for lit")
+    set(LLVM_LIT_ARGS      "${LIBCXXABI_LIT_ARGS}" CACHE STRING "Default options for lit")
   endif()
 
   # Required doc configuration
diff --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt
--- a/libunwind/CMakeLists.txt
+++ b/libunwind/CMakeLists.txt
@@ -102,7 +102,13 @@
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
     endif()
-    set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
+
+    if (DEFINED LIBUNWIND_LIT_ARGS)
+      # libunwind-specific LIT args always win over generic LIT args
+      set(LLVM_LIT_ARGS "${LIBUNWIND_LIT_ARGS}")
+    endif()
+    set(LIBUNWIND_LIT_ARGS "${LIT_ARGS_DEFAULT}"   CACHE STRING "libunwind-specific options for lit")
+    set(LLVM_LIT_ARGS      "${LIBUNWIND_LIT_ARGS}" CACHE STRING "Default options for lit")
 
     # On Win32 hosts, provide an option to specify the path to the GnuWin32 tools.
     if (WIN32 AND NOT CYGWIN)