diff --git a/libcxx/cmake/Modules/HandleCompilerRT.cmake b/libcxx/cmake/Modules/HandleCompilerRT.cmake
index e9da3c43a211..2e0e69e5e085 100644
--- a/libcxx/cmake/Modules/HandleCompilerRT.cmake
+++ b/libcxx/cmake/Modules/HandleCompilerRT.cmake
@@ -14,6 +14,7 @@ function(find_compiler_rt_library name dest)
       OUTPUT_VARIABLE LIBRARY_FILE
   )
   string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
+  file(TO_CMAKE_PATH "${LIBRARY_FILE}" LIBRARY_FILE)
   string(REPLACE "builtins" "${name}" LIBRARY_FILE "${LIBRARY_FILE}")
   if (NOT HAD_ERROR AND EXISTS "${LIBRARY_FILE}")
     message(STATUS "Found compiler-rt library: ${LIBRARY_FILE}")
@@ -37,6 +38,7 @@ function(find_compiler_rt_dir dest)
         OUTPUT_VARIABLE LIBRARY_DIR
     )
     string(STRIP "${LIBRARY_DIR}" LIBRARY_DIR)
+    file(TO_CMAKE_PATH "${LIBRARY_DIR}" LIBRARY_DIR)
     set(LIBRARY_DIR "${LIBRARY_DIR}/darwin")
   else()
     set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBCXX_COMPILE_FLAGS}
@@ -47,6 +49,7 @@ function(find_compiler_rt_dir dest)
         OUTPUT_VARIABLE LIBRARY_FILE
     )
     string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
+    file(TO_CMAKE_PATH "${LIBRARY_FILE}" LIBRARY_FILE)
     get_filename_component(LIBRARY_DIR "${LIBRARY_FILE}" DIRECTORY)
   endif()
   if (NOT HAD_ERROR AND EXISTS "${LIBRARY_DIR}")
diff --git a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
index 83948b14fd1f..70eed1d70ba1 100644
--- a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -46,10 +46,11 @@ macro(find_llvm_parts)
       OUTPUT_VARIABLE CONFIG_OUTPUT
       ERROR_QUIET)
     if(NOT HAD_ERROR)
-      string(STRIP "${CONFIG_OUTPUT}" LLVM_CMAKE_PATH)
+      string(STRIP "${CONFIG_OUTPUT}" LLVM_CMAKE_PATH_FROM_LLVM_CONFIG)
+      file(TO_CMAKE_PATH "${LLVM_CMAKE_PATH_FROM_LLVM_CONFIG}" LLVM_CMAKE_PATH)
     else()
-      set(LLVM_CMAKE_PATH
-          "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm")
+      file(TO_CMAKE_PATH "${LLVM_BINARY_DIR}" LLVM_BINARY_DIR_CMAKE_STYLE)
+      set(LLVM_CMAKE_PATH "${LLVM_BINARY_DIR_CMAKE_STYLE}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm")
     endif()
   else()
     set(LLVM_FOUND OFF)