Index: cmake/modules/CopyDir.cmake
===================================================================
--- cmake/modules/CopyDir.cmake
+++ cmake/modules/CopyDir.cmake
@@ -16,10 +16,17 @@
   )
 endfunction()
 
+# On Windows create_symlink requires special permissions. Use copy_if_different instead.
+if(CMAKE_HOST_WIN32)
+  set(_link_or_copy copy_if_different)
+else()
+  set(_link_or_copy create_symlink)
+endif()
+
 function(llvm_create_symlink target to from)
   add_custom_command(
     TARGET ${target} POST_BUILD
-    COMMAND ${CMAKE_COMMAND} -E create_symlink ${from} ${to}
+    COMMAND ${CMAKE_COMMAND} -E ${_link_or_copy} ${from} ${to}
   )
 endfunction()
 
Index: cmake/modules/TestSuite.cmake
===================================================================
--- cmake/modules/TestSuite.cmake
+++ cmake/modules/TestSuite.cmake
@@ -65,8 +65,8 @@
 
   if(TEST_SUITE_LLVM_SIZE)
     add_custom_command(TARGET ${target} POST_BUILD
-      COMMAND ${TEST_SUITE_LLVM_SIZE} --format=sysv $<TARGET_FILE:${target}>
-      > $<TARGET_FILE:${target}>.size)
+      COMMAND ${TEST_SUITE_LLVM_SIZE} --format=sysv $<SHELL_PATH:$<TARGET_FILE:${target}>>
+      > $<SHELL_PATH:$<TARGET_FILE:${target}>>.size)
   endif()
 endfunction()