diff --git a/clang/Sema/SemaStmt.cpp b/clang/Sema/SemaStmt.cpp
index f7aa6a9e272f..00685c282458 100644
--- a/clang/Sema/SemaStmt.cpp
+++ b/clang/Sema/SemaStmt.cpp
@@ -655,8 +655,40 @@ Sema::StmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
                                     ExprTy **Clobbers,
                                     SourceLocation RParenLoc) {
   Expr *E = (Expr *)AsmString;
+
+  // Check that the output exprs are valid lvalues.
+  for (unsigned i = 0; i < NumOutputs; i++) {
+    Expr *OutputExpr = (Expr *)Exprs[i];
+    Expr::isLvalueResult Result = OutputExpr->isLvalue();
     
-  // FIXME: Make sure that the expressions are valid.
+    if (Result != Expr::LV_Valid) {
+      ParenExpr *PE = cast<ParenExpr>(OutputExpr);
+      
+      Diag(PE->getSubExpr()->getLocStart(), 
+           diag::err_invalid_lvalue_in_asm_output,
+           PE->getSubExpr()->getSourceRange());
+      
+      // FIXME: We currently leak memory here.
+      return true;
+    }
+  }
+  
+  // Check that the input exprs aren't of type void.
+  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
+    Expr *InputExpr = (Expr *)Exprs[i];
+    
+    if (InputExpr->getType()->isVoidType()) {
+      ParenExpr *PE = cast<ParenExpr>(InputExpr);
+      
+      Diag(PE->getSubExpr()->getLocStart(),
+           diag::err_invalid_type_in_asm_input,
+           PE->getType().getAsString(), 
+           PE->getSubExpr()->getSourceRange());
+      
+      // FIXME: We currently leak memory here.
+      return true;
+    }
+  }
   
   return new AsmStmt(AsmLoc,
                      NumOutputs,
diff --git a/clang/include/clang/Basic/DiagnosticKinds.def b/clang/include/clang/Basic/DiagnosticKinds.def
index a6e90b30255b..31fdd27b670f 100644
--- a/clang/include/clang/Basic/DiagnosticKinds.def
+++ b/clang/include/clang/Basic/DiagnosticKinds.def
@@ -789,6 +789,10 @@ DIAG(warn_unused_expr, WARNING,
      "expression result unused")
 DIAG(err_pascal_string_too_long, ERROR,
     "Pascal string is too long")
+DIAG(err_invalid_lvalue_in_asm_output, ERROR,
+    "invalid lvalue in asm output")
+DIAG(err_invalid_type_in_asm_input, ERROR,
+    "invalid type '%0' in asm input")
 
 // CHECK: printf format string errors
 DIAG(warn_printf_not_string_constant, WARNING,
diff --git a/clang/test/Sema/asm.c b/clang/test/Sema/asm.c
new file mode 100644
index 000000000000..e01a0f2dc0de
--- /dev/null
+++ b/clang/test/Sema/asm.c
@@ -0,0 +1,14 @@
+// RUN: clang %s -verify -fsyntax-only
+
+void
+f()
+{
+  int i;
+
+  asm ("foo\n" : : "a" (i + 2));
+  asm ("foo\n" : : "a" (f())); // expected-error {{invalid type 'void' in asm input}}
+  
+  asm ("foo\n" : "=a" (f())); // expected-error {{invalid lvalue in asm output}}
+  asm ("foo\n" : "=a" (i + 2)); // expected-error {{invalid lvalue in asm output}}
+  
+}