Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -679,8 +679,8 @@
   list(FIND LLVM_ALL_TARGETS ${t} idx)
   list(FIND LLVM_EXPERIMENTAL_TARGETS_TO_BUILD ${t} idy)
   if( idx LESS 0 AND idy LESS 0 )
-    message(FATAL_ERROR "The target `${t}' does not exist.
-    It should be one of\n${LLVM_ALL_TARGETS}")
+    message(FATAL_ERROR "The target `${t}' is experimental and must be passed "
+      "via LLVM_EXPERIMENTAL_TARGETS_TO_BUILD.")
   else()
     set(LLVM_ENUM_TARGETS "${LLVM_ENUM_TARGETS}LLVM_TARGET(${t})\n")
   endif()