diff --git a/llvm/cmake/modules/LLVM-Config.cmake b/llvm/cmake/modules/LLVM-Config.cmake
--- a/llvm/cmake/modules/LLVM-Config.cmake
+++ b/llvm/cmake/modules/LLVM-Config.cmake
@@ -28,7 +28,9 @@
     string(TOUPPER "${LLVM_TARGETS_TO_BUILD}" targets)
   elseif(ARG_OMITTED_TARGETS)
     set(omitted_targets ${LLVM_ALL_TARGETS})
-    list(REMOVE_ITEM omitted_targets ${LLVM_TARGETS_TO_BUILD})
+    if (LLVM_TARGETS_TO_BUILD)
+      list(REMOVE_ITEM omitted_targets ${LLVM_TARGETS_TO_BUILD})
+    endif()
     string(TOUPPER "${omitted_targets}" targets)
   else()
     string(TOUPPER "${LLVM_ALL_TARGETS}" targets)