diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -360,21 +360,28 @@
   }
 }
 
-// TODO: implement an iterative version
-static void topologicalSortImpl(llvm::SetVector<Block *> &blocks, Block *b) {
-  blocks.insert(b);
-  for (Block *bb : b->getSuccessors()) {
-    if (blocks.count(bb) == 0)
-      topologicalSortImpl(blocks, bb);
+static void topologicalSortImpl(llvm::SetVector<Block *> &blocks, Block *root) {
+  llvm::SmallVector<Block *, 8> stack;
+  stack.push_back(root);
+
+  while (!stack.empty()) {
+    Block *b = std::move(stack.back());
+    stack.pop_back();
+    blocks.insert(b);
+
+    for (Block *succ : b->getSuccessors()) {
+      if (blocks.count(succ) == 0)
+        stack.push_back(succ);
+    }
   }
 }
 
 /// Sort function blocks topologically.
 template <typename T>
 static llvm::SetVector<Block *> topologicalSort(T &f) {
-  // For each blocks that has not been visited yet (i.e. that has no
-  // predecessors), add it to the list and traverse its successors in DFS
-  // preorder.
+  // For each block that has not been visited yet (i.e. that has no
+  // predecessors), add it to the list and traverse its successors iteratively
+  // in DFS preorder.
   llvm::SetVector<Block *> blocks;
   for (Block &b : f) {
     if (blocks.count(&b) == 0)