Index: lib/CodeGen/CGStmt.cpp
===================================================================
--- lib/CodeGen/CGStmt.cpp
+++ lib/CodeGen/CGStmt.cpp
@@ -2210,7 +2210,7 @@
                    llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize));
         Tmp = Builder.CreateTrunc(Tmp, TruncTy);
       } else if (TruncTy->isIntegerTy()) {
-        Tmp = Builder.CreateTrunc(Tmp, TruncTy);
+        Tmp = Builder.CreateZExtOrTrunc(Tmp, TruncTy);
       } else if (TruncTy->isVectorTy()) {
         Tmp = Builder.CreateBitCast(Tmp, TruncTy);
       }
Index: test/CodeGen/pr34021.c
===================================================================
--- test/CodeGen/pr34021.c
+++ test/CodeGen/pr34021.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fms-extensions %s -triple=i686-unknown-unknown -emit-llvm -o -
+// RUN: %clang_cc1 -fms-extensions %s -triple=x86_64-unknown-unknown -emit-llvm -o -
+// REQUIRES: asserts
+
+typedef int v4si __attribute__ ((vector_size (16)));
+v4si rep() {
+    v4si res;
+    __asm {}
+    return res;
+}