diff --git a/clang/CodeGen/CGBuiltin.cpp b/clang/CodeGen/CGBuiltin.cpp
index a1d5af19dda3..27c82e8cd03c 100644
--- a/clang/CodeGen/CGBuiltin.cpp
+++ b/clang/CodeGen/CGBuiltin.cpp
@@ -100,6 +100,18 @@ RValue CodeGenFunction::EmitBuiltinExpr(unsigned BuiltinID, const CallExpr *E) {
     llvm::Value *Condition = EmitScalarExpr(E->getArg(0));   
     return RValue::get(Condition);
   }
+  case Builtin::BI__builtin_bswap32:
+  case Builtin::BI__builtin_bswap64: {
+    llvm::Value *ArgValue = EmitScalarExpr(E->getArg(0));
+    const llvm::Type *ArgType = ArgValue->getType();
+    llvm::Value *F = 
+      llvm::Intrinsic::getDeclaration(&CGM.getModule(), 
+                                      llvm::Intrinsic::bswap,
+                                      &ArgType, 1);
+    llvm::Value *V = Builder.CreateCall(F, ArgValue, "tmp");
+      
+    return RValue::get(V);      
+  }
   }
   
   return RValue::get(0);
diff --git a/clang/include/clang/AST/Builtins.def b/clang/include/clang/AST/Builtins.def
index 29d0b06f89db..501ab22f7a04 100644
--- a/clang/include/clang/AST/Builtins.def
+++ b/clang/include/clang/AST/Builtins.def
@@ -74,6 +74,8 @@ BUILTIN(__builtin_ctzll, "iULLi", "nc")
 
 
 // Random GCC builtins
+BUILTIN(__builtin_bswap32, "UiUi", "nc")
+BUILTIN(__builtin_bswap64, "ULLiULLi", "nc")
 BUILTIN(__builtin_constant_p, "UsUs", "nc")
 BUILTIN(__builtin_classify_type, "i.", "nc")
 BUILTIN(__builtin___CFStringMakeConstantString, "FC*cC*", "nc")