diff --git a/mlir/include/mlir/IR/Builders.h b/mlir/include/mlir/IR/Builders.h
--- a/mlir/include/mlir/IR/Builders.h
+++ b/mlir/include/mlir/IR/Builders.h
@@ -188,13 +188,23 @@
     setInsertionPoint(op);
   }
 
-  explicit OpBuilder(Block *block) : OpBuilder(block, block->end()) {}
-
   OpBuilder(Block *block, Block::iterator insertPoint)
       : OpBuilder(block->getParent()) {
     setInsertionPoint(block, insertPoint);
   }
 
+  /// Create a builder and set the insertion point to before the first operation
+  /// in the block but still inside th block.
+  static OpBuilder atBlockBegin(Block *block) {
+    return OpBuilder(block, block->begin());
+  }
+
+  /// Create a builder and set the insertion point to after the last operation
+  /// in the block but still inside the block.
+  static OpBuilder atBlockEnd(Block *block) {
+    return OpBuilder(block, block->end());
+  }
+
   /// This class represents a saved insertion point.
   class InsertPoint {
   public:
diff --git a/mlir/lib/Dialect/SPIRV/SPIRVOps.cpp b/mlir/lib/Dialect/SPIRV/SPIRVOps.cpp
--- a/mlir/lib/Dialect/SPIRV/SPIRVOps.cpp
+++ b/mlir/lib/Dialect/SPIRV/SPIRVOps.cpp
@@ -2076,7 +2076,7 @@
   body().push_back(new Block());
   auto *mergeBlock = new Block();
   body().push_back(mergeBlock);
-  OpBuilder builder(mergeBlock);
+  OpBuilder builder = OpBuilder::atBlockEnd(mergeBlock);
 
   // Add a spv._merge op into the merge block.
   builder.create<spirv::MergeOp>(getLoc());
@@ -2373,7 +2373,7 @@
   assert(body().empty() && "entry and merge block already exist");
   auto *mergeBlock = new Block();
   body().push_back(mergeBlock);
-  OpBuilder builder(mergeBlock);
+  OpBuilder builder = OpBuilder::atBlockEnd(mergeBlock);
 
   // Add a spv._merge op into the merge block.
   builder.create<spirv::MergeOp>(getLoc());