diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -387,19 +387,35 @@
     ${ARGN})
 
   if (NOT DEFINED ARG_VERSION_MAJOR)
-    set(ARG_VERSION_MAJOR ${LLVM_VERSION_MAJOR})
+    if (${LLVM_VERSION_MAJOR})
+      set(ARG_VERSION_MAJOR ${LLVM_VERSION_MAJOR})
+    else()
+      set(ARG_VERSION_MAJOR 0)
+    endif()
   endif()
 
   if (NOT DEFINED ARG_VERSION_MINOR)
-    set(ARG_VERSION_MINOR ${LLVM_VERSION_MINOR})
+    if (${LLVM_VERSION_MINOR})
+      set(ARG_VERSION_MINOR ${LLVM_VERSION_MINOR})
+    else()
+      set(ARG_VERSION_MINOR 0)
+    endif()
   endif()
 
   if (NOT DEFINED ARG_VERSION_PATCHLEVEL)
-    set(ARG_VERSION_PATCHLEVEL ${LLVM_VERSION_PATCH})
+    if (${LLVM_VERSION_PATCH})
+      set(ARG_VERSION_PATCHLEVEL ${LLVM_VERSION_PATCH})
+    else()
+      set(ARG_VERSION_PATCHLEVEL 0)
+    endif()
   endif()
 
   if (NOT DEFINED ARG_VERSION_STRING)
-    set(ARG_VERSION_STRING ${PACKAGE_VERSION})
+    if (${PACKAGE_VERSION})
+      set(ARG_VERSION_STRING ${PACKAGE_VERSION})
+    else()
+      set(ARG_VERSION_STRING 0)
+    endif()
   endif()
 
   if (NOT DEFINED ARG_PRODUCT_NAME)