diff --git a/cmake/OpenSimMacros.cmake b/cmake/OpenSimMacros.cmake
index e1b9e537e9..6b935f9c4a 100644
--- a/cmake/OpenSimMacros.cmake
+++ b/cmake/OpenSimMacros.cmake
@@ -390,9 +390,15 @@ function(OpenSimAddTests)
 
         # Copy data files to build directory.
         foreach(data_file ${OSIMADDTESTS_DATAFILES})
-            # This command re-copies the data files if they are modified;
-            # custom commands don't do this.
-            file(COPY "${data_file}" DESTINATION "${CMAKE_CURRENT_BINARY_DIR}")
+            # This command symlinks the data files
+            # from the source directories into the running directory.
+            # This preserves changes to source files.
+            get_filename_component(FILENAME ${data_file} NAME)
+            add_custom_command(
+                TARGET ${TEST_NAME} POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E create_symlink
+                    "${data_file}" 
+                    "${CMAKE_CURRENT_BINARY_DIR}/${FILENAME}")
         endforeach()
 
         #if(UNIX)