diff --git a/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp b/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp
--- a/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Transforms/SparseBufferRewriting.cpp
@@ -567,6 +567,18 @@
 
       Value newBuffer =
           rewriter.create<memref::ReallocOp>(loc, bufferType, buffer, capacity);
+      // Initialize the buffer to support debugging.
+      const char *envStr = std::getenv("SPARSE_TENSOR_INITIALIZE_BUFFER");
+      if (envStr && strcmp(envStr, "1") == 0) {
+        Value fillSize = rewriter.create<arith::SubIOp>(loc, capacity, newSize);
+        Value fillValue = rewriter.create<arith::ConstantOp>(
+            loc, value.getType(), rewriter.getZeroAttr(value.getType()));
+        Value subBuffer = rewriter.create<memref::SubViewOp>(
+            loc, newBuffer, /*offset=*/ValueRange{newSize},
+            /*size=*/ValueRange{fillSize},
+            /*step=*/ValueRange{constantIndex(rewriter, loc, 1)});
+        rewriter.create<linalg::FillOp>(loc, fillValue, subBuffer);
+      }
       rewriter.create<scf::YieldOp>(loc, newBuffer);
 
       // False branch.