diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 78b963c16ffb..0a6cee900b46 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2438,9 +2438,10 @@ static void handleVisibilityAttr(Sema &S, Decl *D, const AttributeList &Attr,
   if (!checkAttributeNumArgs(S, Attr, 1))
     return;
 
-  Expr *Arg = Attr.getArgAsExpr(0);
-  Arg = Arg->IgnoreParenCasts();
-  StringLiteral *Str = dyn_cast<StringLiteral>(Arg);
+  // Check that the argument is a string literal.
+  StringLiteral *Str = 0;
+  if (Attr.isArgExpr(0))
+    Str = dyn_cast<StringLiteral>(Attr.getArgAsExpr(0)->IgnoreParenCasts());
 
   if (!Str || !Str->isAscii()) {
     S.Diag(Attr.getLoc(), diag::err_attribute_argument_type)
diff --git a/clang/test/Sema/attr-visibility.c b/clang/test/Sema/attr-visibility.c
index 7f7fd546f095..ed52ec2743f9 100644
--- a/clang/test/Sema/attr-visibility.c
+++ b/clang/test/Sema/attr-visibility.c
@@ -24,3 +24,5 @@ extern int test7 __attribute__((visibility("hidden"))); // expected-error {{visi
 typedef int __attribute__((visibility("default"))) bar; // expected-warning {{'visibility' attribute ignored}}
 
 int x __attribute__((type_visibility("default"))); // expected-error {{'type_visibility' attribute only applies to types and namespaces}}
+
+int PR17105 __attribute__((visibility(hidden))); // expected-error {{'visibility' attribute requires a string}}