diff --git a/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td b/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
--- a/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
+++ b/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
@@ -142,7 +142,6 @@
   let results = (outs AnyType);
 
   let hasFolder = 1;
-  // TODO: Disallow empty constants.
   let hasVerifier = 1;
 }
 
diff --git a/mlir/lib/Dialect/EmitC/IR/EmitC.cpp b/mlir/lib/Dialect/EmitC/IR/EmitC.cpp
--- a/mlir/lib/Dialect/EmitC/IR/EmitC.cpp
+++ b/mlir/lib/Dialect/EmitC/IR/EmitC.cpp
@@ -125,6 +125,11 @@
   if (getValueAttr().isa<emitc::OpaqueAttr>())
     return success();
 
+  // Value must not be empty
+  StringAttr strAttr = getValueAttr().dyn_cast<StringAttr>();
+  if (strAttr && strAttr.getValue().empty())
+    return emitOpError() << "value must not be empty";
+
   auto value = cast<TypedAttr>(getValueAttr());
   Type type = getType();
   if (!value.getType().isa<NoneType>() && type != value.getType())
diff --git a/mlir/test/Dialect/EmitC/invalid_ops.mlir b/mlir/test/Dialect/EmitC/invalid_ops.mlir
--- a/mlir/test/Dialect/EmitC/invalid_ops.mlir
+++ b/mlir/test/Dialect/EmitC/invalid_ops.mlir
@@ -16,6 +16,14 @@
 
 // -----
 
+func.func @empty_constant() {
+    // expected-error @+1 {{'emitc.constant' op value must not be empty}}
+    %c0 = "emitc.constant"(){value = ""} : () -> i32
+    return
+}
+
+// -----
+
 func.func @index_args_out_of_range_1() {
     // expected-error @+1 {{'emitc.call' op index argument is out of range}}
     emitc.call "test" () {args = [0 : index]} : () -> ()