diff --git a/mlir/include/mlir/Tools/mlir-translate/MlirTranslateMain.h b/mlir/include/mlir/Tools/mlir-translate/MlirTranslateMain.h
--- a/mlir/include/mlir/Tools/mlir-translate/MlirTranslateMain.h
+++ b/mlir/include/mlir/Tools/mlir-translate/MlirTranslateMain.h
@@ -13,16 +13,30 @@
 #ifndef MLIR_TOOLS_MLIRTRANSLATE_MLIRTRANSLATEMAIN_H
 #define MLIR_TOOLS_MLIRTRANSLATE_MLIRTRANSLATEMAIN_H
 
+#include "mlir/IR/Dialect.h"
 #include "mlir/Support/LogicalResult.h"
+#include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/ADT/StringRef.h"
 
 namespace mlir {
+
 /// Translate to/from an MLIR module from/to an external representation (e.g.
 /// LLVM IR, SPIRV binary, ...). This is the entry point for the implementation
 /// of tools like `mlir-translate`. The translation to perform is parsed from
 /// the command line. The `toolName` argument is used for the header displayed
 /// by `--help`.
-LogicalResult mlirTranslateMain(int argc, char **argv, StringRef toolName);
+///
+/// Dialect translation typically registers the dialects produced or returned
+/// by the translation itself, but some translation testing tools may want
+/// additional dialects registered so the .mlir parser can read them.  In this
+/// case, `extraDialects` may be specified with additional dialects to use.
+///
+/// The client may specify a "customization" function if they'd like, which
+/// is invoked when an MLIRContext is set up, allowing custom settings.
+LogicalResult
+mlirTranslateMain(int argc, char **argv, StringRef toolName,
+                  const DialectRegistry &extraDialects = DialectRegistry(),
+                  llvm::function_ref<void(MLIRContext &)> customization = {});
 } // namespace mlir
 
 #endif // MLIR_TOOLS_MLIRTRANSLATE_MLIRTRANSLATEMAIN_H
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
@@ -22,11 +22,13 @@
 using namespace mlir;
 
 //===----------------------------------------------------------------------===//
-// Translation Parser
+// mlir-translate tool driver
 //===----------------------------------------------------------------------===//
 
-LogicalResult mlir::mlirTranslateMain(int argc, char **argv,
-                                      llvm::StringRef toolName) {
+LogicalResult
+mlir::mlirTranslateMain(int argc, char **argv, llvm::StringRef toolName,
+                        const DialectRegistry &extraDialects,
+                        llvm::function_ref<void(MLIRContext &)> customization) {
 
   static llvm::cl::opt<std::string> inputFilename(
       llvm::cl::Positional, llvm::cl::desc("<input file>"),
@@ -80,8 +82,22 @@
   auto processBuffer = [&](std::unique_ptr<llvm::MemoryBuffer> ownedBuffer,
                            raw_ostream &os) {
     MLIRContext context;
-    context.allowUnregisteredDialects(allowUnregisteredDialects);
+
+    // If the client wanted to register additional dialects, go ahead and add
+    // them to our context.
+    context.appendDialectRegistry(extraDialects);
+
+    // If a customization callback was provided, apply it to the MLIRContext.
+    // This could add dialects to the registry or change context defaults.
+    if (customization)
+      customization(context);
+
+    // If command line flags were used to customize the context, apply their
+    // settings.
+    if (allowUnregisteredDialects.getNumOccurrences())
+      context.allowUnregisteredDialects(allowUnregisteredDialects);
     context.printOpOnDiagnostic(!verifyDiagnostics);
+
     llvm::SourceMgr sourceMgr;
     sourceMgr.AddNewSourceBuffer(std::move(ownedBuffer), SMLoc());