diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index d964e89ab8e1c..5ad2a5ad69e8a 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -1618,6 +1618,18 @@ pub fn new_fn_ctxt_w_id(ccx: @mut CrateContext,
         }
     };
     let uses_outptr = type_of::return_uses_outptr(ccx.tcx, substd_output_type);
+
+    // The out pointer will never alias with any other pointers, as the object only exists at a
+    // language level after the call. It can also be tagged with SRet to indicate that it is
+    // guaranteed to point to a usable block of memory for the type.
+    if uses_outptr {
+        unsafe {
+            let outptr = llvm::LLVMGetParam(llfndecl, 0);
+            llvm::LLVMAddAttribute(outptr, lib::llvm::StructRetAttribute as c_uint);
+            llvm::LLVMAddAttribute(outptr, lib::llvm::NoAliasAttribute as c_uint);
+        }
+    }
+
     let debug_context = debuginfo::create_function_debug_context(ccx, id, param_substs, llfndecl);
 
     let fcx = @mut FunctionContext {