diff --git a/CMakeLists.txt b/CMakeLists.txt
index 216702eabaf..53059e63d3d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -347,7 +347,7 @@ set(LLVM_TARGET_ARCH "host"
 
 option(LLVM_ENABLE_TERMINFO "Use terminfo database if available." ON)
 
-option(LLVM_ENABLE_LIBXML2 "Use libxml2 if available." ON)
+set(LLVM_ENABLE_LIBXML2 "ON" CACHE STRING "Use libxml2 if available. Can be ON, OFF, or FORCE_ON")
 
 option(LLVM_ENABLE_LIBEDIT "Use libedit if available." ON)
 
diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index 7f33591de0c..23494fb96c6 100644
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -170,6 +170,10 @@ if( NOT PURE_WINDOWS AND NOT LLVM_USE_SANITIZER MATCHES "Memory.*")
   endif()
 endif()
 
+if (LLVM_ENABLE_LIBXML2 STREQUAL "FORCE_ON" AND NOT LLVM_LIBXML2_ENABLED)
+  message(FATAL_ERROR "Failed to congifure libxml2")
+endif()
+
 check_library_exists(xar xar_open "" HAVE_LIBXAR)
 if(HAVE_LIBXAR)
   set(XAR_LIB xar)