Update CMakeLists.txt

Author: larryliu0820

CMakeLists.txt

@@ -654,20 +654,33 @@ if(EXECUTORCH_BUILD_PYBIND)
   target_compile_options(portable_lib PUBLIC ${_pybind_compile_options})
   target_link_libraries(portable_lib PRIVATE ${_dep_libs})
 
-  # Set RPATH to find PyTorch libraries relative to the installation location
-  # This goes from executorch/extension/pybindings up to site-packages, then to torch/lib
+  
+  # Configure RPATH for portable_lib to find libtorch_python.so at runtime
+  # Strategy: Use relative paths to find torch libraries in the user's environment
+  # not the build environment's torch installation
+  
+  # First, we need to override the global CMAKE_INSTALL_RPATH_USE_LINK_PATH for this target
+  # to prevent build-time paths from being embedded
+  set_target_properties(portable_lib PROPERTIES
+    INSTALL_RPATH_USE_LINK_PATH OFF  # Critical: Don't add build-time library paths
+  )
+  
+  # Set platform-specific relative paths
   if(APPLE)
+    # macOS: use @loader_path for relative paths
+    # @loader_path = directory containing the library itself
     set_target_properties(portable_lib PROPERTIES
-      BUILD_RPATH "@loader_path/../../../torch/lib"
-      INSTALL_RPATH "@loader_path/../../../torch/lib"
+      INSTALL_RPATH "@loader_path;@loader_path/../../../torch/lib"
+      BUILD_WITH_INSTALL_RPATH FALSE  # Use normal build RPATH during build
     )
   else()
+    # Linux: use $ORIGIN for relative paths  
+    # $ORIGIN = directory containing the library itself
     set_target_properties(portable_lib PROPERTIES
-      BUILD_RPATH "$ORIGIN/../../../torch/lib"
-      INSTALL_RPATH "$ORIGIN/../../../torch/lib"
+      INSTALL_RPATH "\$ORIGIN;\$ORIGIN/../../../torch/lib"
+      BUILD_WITH_INSTALL_RPATH FALSE  # Use normal build RPATH during build
     )
   endif()
-
   install(TARGETS portable_lib
           LIBRARY DESTINATION executorch/extension/pybindings
   )