diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
@@ -426,11 +426,7 @@
       result.addAttributes(attributes);
       result.addOperands(operands);
     }]>];
-  let verifier = [{
-    if (getNumResults() > 1)
-      return emitOpError("must have 0 or 1 result");
-    return success();
-  }];
+  let verifier = [{ return ::verify(*this); }];
   let parser = [{ return parseCallOp(parser, result); }];
   let printer = [{ printCallOp(p, *this); }];
 }
diff --git a/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp b/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
--- a/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
+++ b/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
@@ -638,6 +638,17 @@
   return success();
 }
 
+static LogicalResult verify(CallOp op) {
+  if (op.getNumResults() > 1)
+    return op.emitOpError("must have 0 or 1 result");
+
+  if (op.callee().hasValue() &&
+      !SymbolTable::lookupNearestSymbolFrom(op, op.callee().getValue()))
+    return op.emitOpError("calls an undeclared function");
+
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // Printing/parsing for LLVM::ExtractElementOp.
 //===----------------------------------------------------------------------===//
diff --git a/mlir/test/Dialect/LLVMIR/invalid.mlir b/mlir/test/Dialect/LLVMIR/invalid.mlir
--- a/mlir/test/Dialect/LLVMIR/invalid.mlir
+++ b/mlir/test/Dialect/LLVMIR/invalid.mlir
@@ -118,6 +118,13 @@
 
 // -----
 
+func @call_undeclared() {
+  // expected-error@+1 {{calls an undeclared function}}
+  llvm.call @undeclared() : () -> ()
+}
+
+// -----
+
 func @call_non_function_type(%callee : !llvm.func<i8 (i8)>, %arg : !llvm.i8) {
   // expected-error@+1 {{expected function type}}
   llvm.call %callee(%arg) : !llvm.func<i8 (i8)>