diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index a814c9d624c..d7785d5b79c 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -191,21 +191,13 @@ pub fn decl_fn(ccx: &CrateContext, name: &str, cc: llvm::CallConv,
     match ty::get(output).sty {
         // functions returning bottom may unwind, but can never return normally
         ty::ty_bot => {
-            unsafe {
-                llvm::LLVMAddFunctionAttribute(llfn,
-                                               llvm::FunctionIndex as c_uint,
-                                               llvm::NoReturnAttribute as uint64_t)
-            }
+            llvm::SetFunctionAttribute(llfn, llvm::NoReturnAttribute)
         }
         _ => {}
     }
 
     if ccx.tcx().sess.opts.cg.no_redzone {
-        unsafe {
-            llvm::LLVMAddFunctionAttribute(llfn,
-                                           llvm::FunctionIndex as c_uint,
-                                           llvm::NoRedZoneAttribute as uint64_t)
-        }
+        llvm::SetFunctionAttribute(llfn, llvm::NoRedZoneAttribute)
     }
 
     llvm::SetFunctionCallConv(llfn, cc);
diff --git a/src/librustc/middle/trans/foreign.rs b/src/librustc/middle/trans/foreign.rs
index f3049dcee50..9cff7261806 100644
--- a/src/librustc/middle/trans/foreign.rs
+++ b/src/librustc/middle/trans/foreign.rs
@@ -998,7 +998,7 @@ fn add_argument_attributes(tys: &ForeignTypes,
 
     match tys.fn_ty.ret_ty.attr {
         Some(attr) => unsafe {
-            llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr as u64);
+            llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);
         },
         None => {}
     }
@@ -1014,7 +1014,7 @@ fn add_argument_attributes(tys: &ForeignTypes,
 
         match arg_ty.attr {
             Some(attr) => unsafe {
-                llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr as u64);
+                llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);
             },
             None => ()
         }
diff --git a/src/librustc_llvm/lib.rs b/src/librustc_llvm/lib.rs
index 690b288043d..271b19826b6 100644
--- a/src/librustc_llvm/lib.rs
+++ b/src/librustc_llvm/lib.rs
@@ -91,34 +91,35 @@ pub enum DiagnosticSeverity {
     Note,
 }
 
-#[deriving(Clone)]
-pub enum Attribute {
-    ZExtAttribute = 1 << 0,
-    SExtAttribute = 1 << 1,
-    NoReturnAttribute = 1 << 2,
-    InRegAttribute = 1 << 3,
-    StructRetAttribute = 1 << 4,
-    NoUnwindAttribute = 1 << 5,
-    NoAliasAttribute = 1 << 6,
-    ByValAttribute = 1 << 7,
-    NestAttribute = 1 << 8,
-    ReadNoneAttribute = 1 << 9,
-    ReadOnlyAttribute = 1 << 10,
-    NoInlineAttribute = 1 << 11,
-    AlwaysInlineAttribute = 1 << 12,
-    OptimizeForSizeAttribute = 1 << 13,
-    StackProtectAttribute = 1 << 14,
-    StackProtectReqAttribute = 1 << 15,
-    AlignmentAttribute = 31 << 16,
-    NoCaptureAttribute = 1 << 21,
-    NoRedZoneAttribute = 1 << 22,
-    NoImplicitFloatAttribute = 1 << 23,
-    NakedAttribute = 1 << 24,
-    InlineHintAttribute = 1 << 25,
-    StackAttribute = 7 << 26,
-    ReturnsTwiceAttribute = 1 << 29,
-    UWTableAttribute = 1 << 30,
-    NonLazyBindAttribute = 1 << 31,
+bitflags! {
+    flags Attribute : u32 {
+        static ZExtAttribute = 1 << 0,
+        static SExtAttribute = 1 << 1,
+        static NoReturnAttribute = 1 << 2,
+        static InRegAttribute = 1 << 3,
+        static StructRetAttribute = 1 << 4,
+        static NoUnwindAttribute = 1 << 5,
+        static NoAliasAttribute = 1 << 6,
+        static ByValAttribute = 1 << 7,
+        static NestAttribute = 1 << 8,
+        static ReadNoneAttribute = 1 << 9,
+        static ReadOnlyAttribute = 1 << 10,
+        static NoInlineAttribute = 1 << 11,
+        static AlwaysInlineAttribute = 1 << 12,
+        static OptimizeForSizeAttribute = 1 << 13,
+        static StackProtectAttribute = 1 << 14,
+        static StackProtectReqAttribute = 1 << 15,
+        static AlignmentAttribute = 31 << 16,
+        static NoCaptureAttribute = 1 << 21,
+        static NoRedZoneAttribute = 1 << 22,
+        static NoImplicitFloatAttribute = 1 << 23,
+        static NakedAttribute = 1 << 24,
+        static InlineHintAttribute = 1 << 25,
+        static StackAttribute = 7 << 26,
+        static ReturnsTwiceAttribute = 1 << 29,
+        static UWTableAttribute = 1 << 30,
+        static NonLazyBindAttribute = 1 << 31,
+    }
 }
 
 #[repr(u64)]
@@ -160,13 +161,13 @@ trait AttrHelper {
 impl AttrHelper for Attribute {
     fn apply_llfn(&self, idx: c_uint, llfn: ValueRef) {
         unsafe {
-            LLVMAddFunctionAttribute(llfn, idx, *self as uint64_t);
+            LLVMAddFunctionAttribute(llfn, idx, self.bits() as uint64_t);
         }
     }
 
     fn apply_callsite(&self, idx: c_uint, callsite: ValueRef) {
         unsafe {
-            LLVMAddCallSiteAttribute(callsite, idx, *self as uint64_t);
+            LLVMAddCallSiteAttribute(callsite, idx, self.bits() as uint64_t);
         }
     }
 }
@@ -2009,7 +2010,7 @@ pub fn ConstFCmp(pred: RealPredicate, v1: ValueRef, v2: ValueRef) -> ValueRef {
 
 pub fn SetFunctionAttribute(fn_: ValueRef, attr: Attribute) {
     unsafe {
-        LLVMAddFunctionAttribute(fn_, FunctionIndex as c_uint, attr as uint64_t)
+        LLVMAddFunctionAttribute(fn_, FunctionIndex as c_uint, attr.bits() as uint64_t)
     }
 }