diff --git a/llvm/lib/Analysis/CMakeLists.txt b/llvm/lib/Analysis/CMakeLists.txt
--- a/llvm/lib/Analysis/CMakeLists.txt
+++ b/llvm/lib/Analysis/CMakeLists.txt
@@ -14,6 +14,11 @@
       message(WARNING "LLVM_INLINER_MODEL_PATH was not set: autogenerating a model to finish the build.")
     endif()
 
+    # Crash if the user wants to download a model but a URL is not specified
+    if ("${LLVM_INLINER_MODEL_PATH}" STREQUAL "download" AND "${LLVM_INLINER_MODEL_CURRENT_URL}" STREQUAL "")
+        message(FATAL_ERROR "LLVM_INLINER_MODEL_PATH was set to 'download' but there is no model url currently specified in cmake - likely, the model interface recently changed, and so there is not a released model available.")
+    endif()
+
     tf_find_and_compile(
       ${LLVM_INLINER_MODEL_PATH}
       ${LLVM_INLINER_MODEL_CURRENT_URL}