diff --git a/mlir/examples/Linalg/Linalg1/lib/ConvertToLLVMDialect.cpp b/mlir/examples/Linalg/Linalg1/lib/ConvertToLLVMDialect.cpp
index f0908564d957..ad8b768a2d3a 100644
--- a/mlir/examples/Linalg/Linalg1/lib/ConvertToLLVMDialect.cpp
+++ b/mlir/examples/Linalg/Linalg1/lib/ConvertToLLVMDialect.cpp
@@ -422,7 +422,7 @@ void linalg::convertToLLVM(mlir::Module &module) {
   populateLinalg1ToLLVMConversionPatterns(patterns, module.getContext());
 
   ConversionTarget target(*module.getContext());
-  target.addLegalDialects<LLVM::LLVMDialect>();
+  target.addLegalDialect<LLVM::LLVMDialect>();
   auto r =
       applyConversionPatterns(module, target, converter, std::move(patterns));
   (void)r;
diff --git a/mlir/examples/Linalg/Linalg3/lib/ConvertToLLVMDialect.cpp b/mlir/examples/Linalg/Linalg3/lib/ConvertToLLVMDialect.cpp
index 26d6af8b6cc4..7a4edc4e439b 100644
--- a/mlir/examples/Linalg/Linalg3/lib/ConvertToLLVMDialect.cpp
+++ b/mlir/examples/Linalg/Linalg3/lib/ConvertToLLVMDialect.cpp
@@ -163,7 +163,7 @@ void linalg::convertLinalg3ToLLVM(Module &module) {
   populateLinalg3ToLLVMConversionPatterns(patterns, module.getContext());
 
   ConversionTarget target(*module.getContext());
-  target.addLegalDialects<LLVM::LLVMDialect>();
+  target.addLegalDialect<LLVM::LLVMDialect>();
   auto r =
       applyConversionPatterns(module, target, converter, std::move(patterns));
   (void)r;
diff --git a/mlir/examples/toy/Ch5/mlir/EarlyLowering.cpp b/mlir/examples/toy/Ch5/mlir/EarlyLowering.cpp
index 82541f80c3e4..e8ce2a4ed52a 100644
--- a/mlir/examples/toy/Ch5/mlir/EarlyLowering.cpp
+++ b/mlir/examples/toy/Ch5/mlir/EarlyLowering.cpp
@@ -127,7 +127,7 @@ public:
 struct EarlyLoweringPass : public FunctionPass<EarlyLoweringPass> {
   void runOnFunction() override {
     ConversionTarget target(getContext());
-    target.addLegalDialects<linalg::LinalgDialect, StandardOpsDialect>();
+    target.addLegalDialect<linalg::LinalgDialect, StandardOpsDialect>();
     target.addLegalOp<toy::AllocOp, toy::TypeCastOp>();
 
     OwningRewritePatternList patterns;
diff --git a/mlir/examples/toy/Ch5/mlir/LateLowering.cpp b/mlir/examples/toy/Ch5/mlir/LateLowering.cpp
index 4434e1bde58b..b2160898f520 100644
--- a/mlir/examples/toy/Ch5/mlir/LateLowering.cpp
+++ b/mlir/examples/toy/Ch5/mlir/LateLowering.cpp
@@ -345,8 +345,8 @@ struct LateLoweringPass : public ModulePass<LateLoweringPass> {
 
     // Perform Toy specific lowering.
     ConversionTarget target(getContext());
-    target.addLegalDialects<AffineOpsDialect, linalg::LinalgDialect,
-                            LLVM::LLVMDialect, StandardOpsDialect>();
+    target.addLegalDialect<AffineOpsDialect, linalg::LinalgDialect,
+                           LLVM::LLVMDialect, StandardOpsDialect>();
     target.addLegalOp<toy::AllocOp, toy::TypeCastOp>();
     if (failed(applyConversionPatterns(getModule(), target, typeConverter,
                                        std::move(toyPatterns)))) {
diff --git a/mlir/include/mlir/Transforms/DialectConversion.h b/mlir/include/mlir/Transforms/DialectConversion.h
index e95842652d98..363f96d66c23 100644
--- a/mlir/include/mlir/Transforms/DialectConversion.h
+++ b/mlir/include/mlir/Transforms/DialectConversion.h
@@ -180,9 +180,7 @@ public:
   //===--------------------------------------------------------------------===//
 
   /// Register a legality action for the given operation.
-  void setOpAction(OperationName op, LegalizationAction action) {
-    legalOperations[op] = action;
-  }
+  void setOpAction(OperationName op, LegalizationAction action);
   template <typename OpT> void setOpAction(LegalizationAction action) {
     setOpAction(OperationName(OpT::getOperationName(), &ctx), action);
   }
@@ -196,21 +194,6 @@ public:
     addLegalOp<OpT2, OpTs...>();
   }
 
-  /// Register the operations of the given dialects as legal.
-  void addLegalDialects(ArrayRef<StringRef> dialectNames) {
-    for (auto &dialect : dialectNames)
-      legalDialects[dialect] = LegalizationAction::Legal;
-  }
-  template <typename... Names>
-  void addLegalDialects(StringRef name, Names... names) {
-    SmallVector<StringRef, 2> dialectNames({name, names...});
-    addLegalDialects(dialectNames);
-  }
-  template <typename... Args> void addLegalDialects() {
-    SmallVector<StringRef, 2> dialectNames({Args::getDialectNamespace()...});
-    addLegalDialects(dialectNames);
-  }
-
   /// Register the given operation as dynamically legal, i.e. requiring custom
   /// handling by the target via 'isLegal'.
   template <typename OpT> void addDynamicallyLegalOp() {
@@ -222,22 +205,39 @@ public:
     addDynamicallyLegalOp<OpT2, OpTs...>();
   }
 
+  /// Register a legality action for the given dialects.
+  void setDialectAction(ArrayRef<StringRef> dialectNames,
+                        LegalizationAction action);
+
+  /// Register the operations of the given dialects as legal.
+  template <typename... Names>
+  void addLegalDialect(StringRef name, Names... names) {
+    SmallVector<StringRef, 2> dialectNames({name, names...});
+    setDialectAction(dialectNames, LegalizationAction::Legal);
+  }
+  template <typename... Args> void addLegalDialect() {
+    SmallVector<StringRef, 2> dialectNames({Args::getDialectNamespace()...});
+    setDialectAction(dialectNames, LegalizationAction::Legal);
+  }
+
+  /// Register the operations of the given dialects as dynamically legal, i.e.
+  /// requiring custom handling by the target via 'isLegal'.
+  template <typename... Names>
+  void addDynamicallyLegalDialect(StringRef name, Names... names) {
+    SmallVector<StringRef, 2> dialectNames({name, names...});
+    setDialectAction(dialectNames, LegalizationAction::Dynamic);
+  }
+  template <typename... Args> void addDynamicallyLegalDialect() {
+    SmallVector<StringRef, 2> dialectNames({Args::getDialectNamespace()...});
+    setDialectAction(dialectNames, LegalizationAction::Dynamic);
+  }
+
   //===--------------------------------------------------------------------===//
   // Legality Querying
   //===--------------------------------------------------------------------===//
 
   /// Get the legality action for the given operation.
-  llvm::Optional<LegalizationAction> getOpAction(OperationName op) const {
-    // Check for an action for this specific operation.
-    auto it = legalOperations.find(op);
-    if (it != legalOperations.end())
-      return it->second;
-    // Otherwise, default to checking for an action on the parent dialect.
-    auto dialectIt = legalDialects.find(op.getDialect());
-    if (dialectIt != legalDialects.end())
-      return dialectIt->second;
-    return llvm::None;
-  }
+  llvm::Optional<LegalizationAction> getOpAction(OperationName op) const;
 
 private:
   /// A deterministic mapping of operation name to the specific legality action
diff --git a/mlir/lib/LLVMIR/Transforms/ConvertToLLVMDialect.cpp b/mlir/lib/LLVMIR/Transforms/ConvertToLLVMDialect.cpp
index dd91f069849b..6fbdba38428a 100644
--- a/mlir/lib/LLVMIR/Transforms/ConvertToLLVMDialect.cpp
+++ b/mlir/lib/LLVMIR/Transforms/ConvertToLLVMDialect.cpp
@@ -994,7 +994,7 @@ struct LLVMLoweringPass : public ModulePass<LLVMLoweringPass> {
     populateStdToLLVMConversionPatterns(converter, patterns);
 
     ConversionTarget target(getContext());
-    target.addLegalDialects<LLVM::LLVMDialect>();
+    target.addLegalDialect<LLVM::LLVMDialect>();
     if (failed(
             applyConversionPatterns(m, target, converter, std::move(patterns))))
       signalPassFailure();
diff --git a/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp b/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp
index 60c16d9eab16..2093acfdf775 100644
--- a/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp
+++ b/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp
@@ -689,7 +689,7 @@ void LowerLinalgToLLVMPass::runOnModule() {
   populateLinalgToLLVMConversionPatterns(converter, patterns, &getContext());
 
   ConversionTarget target(getContext());
-  target.addLegalDialects<LLVM::LLVMDialect>();
+  target.addLegalDialect<LLVM::LLVMDialect>();
   if (failed(applyConversionPatterns(module, target, converter,
                                      std::move(patterns))))
     signalPassFailure();
diff --git a/mlir/lib/Transforms/DialectConversion.cpp b/mlir/lib/Transforms/DialectConversion.cpp
index 5d2a889c4946..3a19692f190a 100644
--- a/mlir/lib/Transforms/DialectConversion.cpp
+++ b/mlir/lib/Transforms/DialectConversion.cpp
@@ -724,6 +724,37 @@ FunctionType TypeConverter::convertFunctionSignatureType(
   return FunctionType::get(arguments, results, type.getContext());
 }
 
+//===----------------------------------------------------------------------===//
+// ConversionTarget
+//===----------------------------------------------------------------------===//
+
+/// Register a legality action for the given operation.
+void ConversionTarget::setOpAction(OperationName op,
+                                   LegalizationAction action) {
+  legalOperations[op] = action;
+}
+
+/// Register a legality action for the given dialects.
+void ConversionTarget::setDialectAction(ArrayRef<StringRef> dialectNames,
+                                        LegalizationAction action) {
+  for (StringRef dialect : dialectNames)
+    legalDialects[dialect] = action;
+}
+
+/// Get the legality action for the given operation.
+auto ConversionTarget::getOpAction(OperationName op) const
+    -> llvm::Optional<LegalizationAction> {
+  // Check for an action for this specific operation.
+  auto it = legalOperations.find(op);
+  if (it != legalOperations.end())
+    return it->second;
+  // Otherwise, default to checking for an action on the parent dialect.
+  auto dialectIt = legalDialects.find(op.getDialect());
+  if (dialectIt != legalDialects.end())
+    return dialectIt->second;
+  return llvm::None;
+}
+
 //===----------------------------------------------------------------------===//
 // applyConversionPatterns
 //===----------------------------------------------------------------------===//
diff --git a/mlir/lib/Transforms/LowerAffine.cpp b/mlir/lib/Transforms/LowerAffine.cpp
index ac2227dbdb8b..4d9df82b27ae 100644
--- a/mlir/lib/Transforms/LowerAffine.cpp
+++ b/mlir/lib/Transforms/LowerAffine.cpp
@@ -597,7 +597,7 @@ LogicalResult mlir::lowerAffineConstructs(Function &function) {
                      AffineTerminatorLowering>::build(patterns,
                                                       function.getContext());
   ConversionTarget target(*function.getContext());
-  target.addLegalDialects<StandardOpsDialect>();
+  target.addLegalDialect<StandardOpsDialect>();
   return applyConversionPatterns(function, target, std::move(patterns));
 }