diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -2467,7 +2467,8 @@
     // that is usually cheaper, but LLVM IR should really get an anyext someday.
     if (Info.hasTiedOperand()) {
       unsigned Output = Info.getTiedOperand();
-      QualType OutputType = S.getOutputExpr(Output)->getType();
+      const Expr *OutputExpr = S.getOutputExpr(Output);
+      QualType OutputType = OutputExpr->getType();
       QualType InputTy = InputExpr->getType();
 
       if (getContext().getTypeSize(OutputType) >
@@ -2480,10 +2481,14 @@
           Arg = Builder.CreateZExt(Arg, OutputTy);
         else if (isa<llvm::PointerType>(OutputTy))
           Arg = Builder.CreateZExt(Arg, IntPtrTy);
-        else {
-          assert(OutputTy->isFloatingPointTy() && "Unexpected output type");
+        else if (OutputTy->isFloatingPointTy())
           Arg = Builder.CreateFPExt(Arg, OutputTy);
-        }
+        else
+          // FIXME: GCC and ICC can handle structure type that have more than 1
+          // element. We may need to match the same behavior.
+          CGM.getDiags().Report(S.getAsmLoc(), diag::err_asm_invalid_type)
+              << OutputExpr->getType() << 1 /*Output*/
+              << OutputExpr->getSourceRange();
       }
       // Deal with the tied operands' constraint code in adjustInlineAsmType.
       ReplaceConstraint = OutputConstraints[Output];
diff --git a/clang/lib/Sema/SemaStmtAsm.cpp b/clang/lib/Sema/SemaStmtAsm.cpp
--- a/clang/lib/Sema/SemaStmtAsm.cpp
+++ b/clang/lib/Sema/SemaStmtAsm.cpp
@@ -666,7 +666,8 @@
     // output was a register, just extend the shorter one to the size of the
     // larger one.
     if (!SmallerValueMentioned && InputDomain != AD_Other &&
-        OutputConstraintInfos[TiedTo].allowsRegister())
+        OutputConstraintInfos[TiedTo].allowsRegister() &&
+        (OutputDomain != AD_Other || OutSize <= InSize))
       continue;
 
     // Either both of the operands were mentioned or the smaller one was
diff --git a/clang/test/Sema/asm.c b/clang/test/Sema/asm.c
--- a/clang/test/Sema/asm.c
+++ b/clang/test/Sema/asm.c
@@ -313,3 +313,23 @@
   asm ("jne %l0":::);
   asm goto ("jne %l0"::::lab);
 }
+
+// FIXME: GCC and ICC support this case. We may need to follow them.
+typedef struct test19_foo {
+  int a;
+  char b;
+} test19_foo;
+
+typedef struct test19_bar {
+  int a;
+  int b;
+  int c;
+} test19_bar;
+
+void test19()
+{
+  test19_foo a;
+  test19_bar b;
+  asm ("" : "=rm" (a): "0" (1)); // expected-error {{unsupported inline asm: input with type 'int' matching output with type 'test19_foo' (aka 'struct test19_foo')}}
+  asm ("" : "=rm" (b): "0" (1)); // expected-error {{unsupported inline asm: input with type 'int' matching output with type 'test19_bar' (aka 'struct test19_bar')}}
+}