diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -574,6 +574,9 @@
   # Set this variable to OFF here so it can't be set with a command-line
   # argument.
   set (LLVM_LINK_LLVM_DYLIB OFF)
+  if (BUILD_SHARED_LIBS)
+    message(FATAL_ERROR "BUILD_SHARED_LIBS options is not supported on Windows.")
+  endif()
 else()
   option(LLVM_LINK_LLVM_DYLIB "Link tools against the libllvm dynamic library" OFF)
   option(LLVM_BUILD_LLVM_C_DYLIB "Build libllvm-c re-export library (Darwin only)" OFF)