diff --git a/mlir/include/mlir/Support/ToolUtilities.h b/mlir/include/mlir/Support/ToolUtilities.h
--- a/mlir/include/mlir/Support/ToolUtilities.h
+++ b/mlir/include/mlir/Support/ToolUtilities.h
@@ -32,10 +32,15 @@
 /// all results to `os`.
 ///
 /// This is used to allow a large number of small independent tests to be put
-/// into a single file.
+/// into a single file. `enableSplitting` can be used to toggle if splitting
+/// should be enabled, e.g. to allow for merging split and non-split code paths.
+/// When `insertMarkerInOutput` is true, split markers (`//-----`) are placed
+/// between each of the processed output chunks.
 LogicalResult
 splitAndProcessBuffer(std::unique_ptr<llvm::MemoryBuffer> originalBuffer,
-                      ChunkBufferHandler processChunkBuffer, raw_ostream &os);
+                      ChunkBufferHandler processChunkBuffer, raw_ostream &os,
+                      bool enableSplitting = true,
+                      bool insertMarkerInOutput = false);
 } // namespace mlir
 
 #endif // MLIR_SUPPORT_TOOLUTILITIES_H
diff --git a/mlir/lib/Support/ToolUtilities.cpp b/mlir/lib/Support/ToolUtilities.cpp
--- a/mlir/lib/Support/ToolUtilities.cpp
+++ b/mlir/lib/Support/ToolUtilities.cpp
@@ -21,7 +21,12 @@
 LogicalResult
 mlir::splitAndProcessBuffer(std::unique_ptr<llvm::MemoryBuffer> originalBuffer,
                             ChunkBufferHandler processChunkBuffer,
-                            raw_ostream &os) {
+                            raw_ostream &os, bool enableSplitting,
+                            bool insertMarkerInOutput) {
+  // If splitting is disabled, we process the full input buffer.
+  if (!enableSplitting)
+    return processChunkBuffer(std::move(originalBuffer), os);
+
   const char splitMarkerConst[] = "// -----";
   StringRef splitMarker(splitMarkerConst);
   const int splitMarkerLen = splitMarker.size();
@@ -73,7 +78,7 @@
 
   // Process each chunk in turn.
   bool hadFailure = false;
-  for (auto &subBuffer : sourceBuffers) {
+  auto interleaveFn = [&](StringRef subBuffer) {
     auto splitLoc = SMLoc::getFromPointer(subBuffer.data());
     unsigned splitLine = fileSourceMgr.getLineAndColumn(splitLoc).first;
     auto subMemBuffer = llvm::MemoryBuffer::getMemBufferCopy(
@@ -82,7 +87,9 @@
                        Twine(splitLine) + " offset ");
     if (failed(processChunkBuffer(std::move(subMemBuffer), os)))
       hadFailure = true;
-  }
+  };
+  llvm::interleave(sourceBuffers, os, interleaveFn,
+                   insertMarkerInOutput ? "\n// -----\n" : "");
 
   // If any fails, then return a failure of the tool.
   return failure(hadFailure);
diff --git a/mlir/lib/Tools/mlir-opt/MlirOptMain.cpp b/mlir/lib/Tools/mlir-opt/MlirOptMain.cpp
--- a/mlir/lib/Tools/mlir-opt/MlirOptMain.cpp
+++ b/mlir/lib/Tools/mlir-opt/MlirOptMain.cpp
@@ -145,6 +145,7 @@
   // We use an explicit threadpool to avoid creating and joining/destroying
   // threads for each of the split.
   ThreadPool *threadPool = nullptr;
+
   // Create a temporary context for the sake of checking if
   // --mlir-disable-threading was passed on the command line.
   // We use the thread-pool this context is creating, and avoid
@@ -153,23 +154,15 @@
   if (threadPoolCtx.isMultithreadingEnabled())
     threadPool = &threadPoolCtx.getThreadPool();
 
-  if (splitInputFile)
-    return splitAndProcessBuffer(
-        std::move(buffer),
-        [&](std::unique_ptr<MemoryBuffer> chunkBuffer, raw_ostream &os) {
-          LogicalResult result = processBuffer(
-              os, std::move(chunkBuffer), verifyDiagnostics, verifyPasses,
-              allowUnregisteredDialects, preloadDialectsInContext,
-              passManagerSetupFn, registry, threadPool);
-          os << "// -----\n";
-          return result;
-        },
-        outputStream);
-
-  return processBuffer(outputStream, std::move(buffer), verifyDiagnostics,
-                       verifyPasses, allowUnregisteredDialects,
-                       preloadDialectsInContext, passManagerSetupFn, registry,
-                       threadPool);
+  auto chunkFn = [&](std::unique_ptr<MemoryBuffer> chunkBuffer,
+                     raw_ostream &os) {
+    return processBuffer(os, std::move(chunkBuffer), verifyDiagnostics,
+                         verifyPasses, allowUnregisteredDialects,
+                         preloadDialectsInContext, passManagerSetupFn, registry,
+                         threadPool);
+  };
+  return splitAndProcessBuffer(std::move(buffer), chunkFn, outputStream,
+                               splitInputFile, /*insertMarkerInOutput=*/true);
 }
 
 LogicalResult mlir::MlirOptMain(raw_ostream &outputStream,
diff --git a/mlir/lib/Tools/mlir-translate/MlirTranslateMain.cpp b/mlir/lib/Tools/mlir-translate/MlirTranslateMain.cpp
--- a/mlir/lib/Tools/mlir-translate/MlirTranslateMain.cpp
+++ b/mlir/lib/Tools/mlir-translate/MlirTranslateMain.cpp
@@ -98,13 +98,9 @@
     return sourceMgrHandler.verify();
   };
 
-  if (splitInputFile) {
-    if (failed(splitAndProcessBuffer(std::move(input), processBuffer,
-                                     output->os())))
-      return failure();
-  } else if (failed(processBuffer(std::move(input), output->os()))) {
+  if (failed(splitAndProcessBuffer(std::move(input), processBuffer,
+                                   output->os(), splitInputFile)))
     return failure();
-  }
 
   output->keep();
   return success();
diff --git a/mlir/tools/mlir-pdll/mlir-pdll.cpp b/mlir/tools/mlir-pdll/mlir-pdll.cpp
--- a/mlir/tools/mlir-pdll/mlir-pdll.cpp
+++ b/mlir/tools/mlir-pdll/mlir-pdll.cpp
@@ -186,13 +186,9 @@
     return processBuffer(os, std::move(chunkBuffer), outputType, includeDirs,
                          dumpODS, includedFiles);
   };
-  if (splitInputFile) {
-    if (failed(splitAndProcessBuffer(std::move(inputFile), processFn,
-                                     outputStrOS)))
-      return 1;
-  } else if (failed(processFn(std::move(inputFile), outputStrOS))) {
+  if (failed(splitAndProcessBuffer(std::move(inputFile), processFn, outputStrOS,
+                                   splitInputFile)))
     return 1;
-  }
 
   // Write the output.
   bool shouldWriteOutput = true;