Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -8579,6 +8579,9 @@
   "invalid prototype, variadic arguments are not allowed in OpenCL">;
 def err_opencl_requires_extension : Error<
   "use of %select{type|declaration}0 %1 requires %2 extension to be enabled">;
+def warn_opencl_generic_address_space_arg : Warning<
+  "passing non-generic address space pointer to %0"
+  " generates dynamic conversion where it is not needed">;
 
 // OpenCL v2.0 s6.13.6 -- Builtin Pipe Functions
 def err_opencl_builtin_pipe_first_arg : Error<
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -839,6 +839,13 @@
     return true;
   }
 
+  if (RT->getPointeeType().getAddressSpace() != LangAS::opencl_generic) {
+    S.Diag(Call->getArg(0)->getLocStart(),
+           diag::warn_opencl_generic_address_space_arg)
+        << Call->getDirectCallee()->getNameInfo().getAsString()
+        << Call->getArg(0)->getSourceRange();
+  }
+
   RT = RT->getPointeeType();
   auto Qual = RT.getQualifiers();
   switch (BuiltinID) {
Index: test/Misc/warning-flags.c
===================================================================
--- test/Misc/warning-flags.c
+++ test/Misc/warning-flags.c
@@ -18,7 +18,7 @@
 
 The list of warnings below should NEVER grow.  It should gradually shrink to 0.
 
-CHECK: Warnings without flags (76):
+CHECK: Warnings without flags (77):
 CHECK-NEXT:   ext_excess_initializers
 CHECK-NEXT:   ext_excess_initializers_in_char_array_initializer
 CHECK-NEXT:   ext_expected_semi_decl_list
@@ -77,6 +77,7 @@
 CHECK-NEXT:   warn_objc_property_copy_missing_on_block
 CHECK-NEXT:   warn_objc_protocol_qualifier_missing_id
 CHECK-NEXT:   warn_on_superclass_use
+CHECK-NEXT:   warn_opencl_generic_address_space_arg
 CHECK-NEXT:   warn_pp_convert_to_positive
 CHECK-NEXT:   warn_pp_expr_overflow
 CHECK-NEXT:   warn_pp_line_decimal
Index: test/SemaOpenCL/to_addr_builtin.cl
===================================================================
--- test/SemaOpenCL/to_addr_builtin.cl
+++ test/SemaOpenCL/to_addr_builtin.cl
@@ -43,6 +43,7 @@
   // expected-warning@-2{{incompatible integer to pointer conversion assigning to '__local int *' from 'int'}}
 #else
   // expected-error@-4{{assigning '__global int *' to '__local int *' changes address space of pointer}}
+  // expected-warning@-5{{passing non-generic address space pointer to to_global generates dynamic conversion where it is not needed}}
 #endif
 
   global char *glob_c = to_global(loc);
@@ -50,6 +51,6 @@
   // expected-warning@-2{{incompatible integer to pointer conversion initializing '__global char *' with an expression of type 'int'}}
 #else
   // expected-warning@-4{{incompatible pointer types initializing '__global char *' with an expression of type '__global int *'}}
+  // expected-warning@-5{{passing non-generic address space pointer to to_global generates dynamic conversion where it is not needed}}
 #endif
-
 }