diff --git a/llvm/include/llvm/module.modulemap b/llvm/include/llvm/module.modulemap
--- a/llvm/include/llvm/module.modulemap
+++ b/llvm/include/llvm/module.modulemap
@@ -420,6 +420,9 @@
     // Exclude this; it should only be used on Windows.
     exclude header "Support/Windows/WindowsSupport.h"
 
+    // Exclude this; it has been replaced by llvm/TargetParser/Host.h.
+    exclude header "Support/Host.h"
+
     // Exclude these; they are fundamentally non-modular.
     exclude header "Support/PluginLoader.h"
     exclude header "Support/Solaris/sys/regset.h"