diff --git a/mlir/include/mlir/Support/IndentedOstream.h b/mlir/include/mlir/Support/IndentedOstream.h
--- a/mlir/include/mlir/Support/IndentedOstream.h
+++ b/mlir/include/mlir/Support/IndentedOstream.h
@@ -113,7 +113,13 @@
 inline raw_indented_ostream &
 mlir::raw_indented_ostream::printReindented(StringRef str,
                                             StringRef extraPrefix) {
-  StringRef output = str;
+  // Before splitting on \n, remove Windows \r characters from \r\n endings.
+  std::string normalizedStr = str.str();
+  normalizedStr.erase(
+      std::remove(normalizedStr.begin(), normalizedStr.end(), '\r'),
+      normalizedStr.cend());
+  StringRef output(normalizedStr);
+
   // Skip empty lines.
   while (!output.empty()) {
     auto split = output.split('\n');
diff --git a/mlir/unittests/Support/IndentedOstreamTest.cpp b/mlir/unittests/Support/IndentedOstreamTest.cpp
--- a/mlir/unittests/Support/IndentedOstreamTest.cpp
+++ b/mlir/unittests/Support/IndentedOstreamTest.cpp
@@ -108,3 +108,19 @@
 )";
   EXPECT_THAT(os.str(), StrEq(expected));
 }
+
+TEST(FormatTest, ReindentLineEndings) {
+  std::string str;
+  llvm::raw_string_ostream os(str);
+  raw_indented_ostream ros(os);
+
+  // Similar string as the previous test, but with \r\n (Windows style) line
+  // breaks. Note that C++'s internal string representation uses \n, so just
+  // running the previous test as-is on Windows is not sufficient.
+  const auto *desc =
+      "\r\n\r\n\r\n         First line\r\n                 second line";
+  ros.printReindented(desc);
+  ros.flush();
+  const auto *expected = "First line\n        second line";
+  EXPECT_THAT(os.str(), StrEq(expected));
+}