diff --git a/include/mlir-hlo/Dialect/mhlo/IR/chlo_ops.td b/include/mlir-hlo/Dialect/mhlo/IR/chlo_ops.td
index 13d5f02..92ae4d2 100644
--- a/include/mlir-hlo/Dialect/mhlo/IR/chlo_ops.td
+++ b/include/mlir-hlo/Dialect/mhlo/IR/chlo_ops.td
@@ -360,19 +360,6 @@ def HLOClient_AcosOp : HLOClient_UnaryElementwiseOp<"acos", [],
   }];
 }
 
-def HLOClient_AtanOp : HLOClient_UnaryElementwiseOp<"atan", [],
-    HLO_FpOrComplexTensor> {
-  let summary = "Atan operator";
-
-  let description = [{
-    Returns `Atan(operand)` element-wise.
-
-    $$
-    \atan(x) = \atan2(x, 1)
-    $$
-  }];
-}
-
 def HLOClient_SinhOp : HLOClient_UnaryElementwiseOp<"sinh", [],
     HLO_FpOrComplexTensor> {
   let summary = "Sinh operation";
diff --git a/include/mlir-hlo/Dialect/mhlo/transforms/map_lmhlo_to_scalar_op.h b/include/mlir-hlo/Dialect/mhlo/transforms/map_lmhlo_to_scalar_op.h
index 9cf1b6c..d2fb048 100644
--- a/include/mlir-hlo/Dialect/mhlo/transforms/map_lmhlo_to_scalar_op.h
+++ b/include/mlir-hlo/Dialect/mhlo/transforms/map_lmhlo_to_scalar_op.h
@@ -149,15 +149,6 @@ inline Value MapLhloOpToStdScalarOp<lmhlo::AndOp>(Location loc,
       loc, result_types, args, b);
 }
 
-template <>
-inline Value MapLhloOpToStdScalarOp<lmhlo::Atan2Op>(Location loc,
-                                                    ArrayRef<Type> result_types,
-                                                    ArrayRef<Value> args,
-                                                    OpBuilder* b) {
-  return MapLhloOpToStdScalarOpImpl<FloatType, ::mlir::Atan2Op>{}(
-      loc, result_types, args, b);
-}
-
 template <typename PredicateType>
 inline Optional<PredicateType> getCmpPredicate(StringRef comparison_direction) {
   return llvm::None;
diff --git a/lib/Dialect/mhlo/transforms/chlo_legalize_to_hlo_patterns.td b/lib/Dialect/mhlo/transforms/chlo_legalize_to_hlo_patterns.td
index fb4bf3a..9d9e6d9 100644
--- a/lib/Dialect/mhlo/transforms/chlo_legalize_to_hlo_patterns.td
+++ b/lib/Dialect/mhlo/transforms/chlo_legalize_to_hlo_patterns.td
@@ -49,14 +49,6 @@ def : Pat<(HLOClient_AcosOp $input),
     ),
     (HLO_ConstantLike<"M_PI"> $input))>;
 
-// Express `atan` as
-//   atan(x) = atan2(x, 1)
-def : Pat<(HLOClient_AtanOp $input),
-  (HLO_Atan2Op
-    $input,
-    (HLO_ConstantLike<"1"> $input)
-  )>;
-
 // Express `sinh` as
 //   sinh(x) = (e^x - e^-x) / 2                     if |x| < 1
 //           = e^(x + log(1/2)) - e^(-x + log(1/2)) otherwise.
@@ -103,3 +95,4 @@ def : Pat<(HLOClient_TanOp $input),
     (HLO_SinOp $input),
     (HLO_CosOp $input)
   )>;
+
diff --git a/lib/Dialect/mhlo/transforms/legalize_to_linalg.cc b/lib/Dialect/mhlo/transforms/legalize_to_linalg.cc
index 57859b6..2d36b1c 100644
--- a/lib/Dialect/mhlo/transforms/legalize_to_linalg.cc
+++ b/lib/Dialect/mhlo/transforms/legalize_to_linalg.cc
@@ -822,7 +822,6 @@ void populateLHLOToLinalgConversionPattern(MLIRContext* context,
                    PointwiseToLinalgConverter<lmhlo::AbsOp>,
                    PointwiseToLinalgConverter<lmhlo::AddOp>,
                    PointwiseToLinalgConverter<lmhlo::AndOp>,
-                   PointwiseToLinalgConverter<lmhlo::Atan2Op>,
                    PointwiseToLinalgConverter<lmhlo::CeilOp>,
                    PointwiseToLinalgConverter<lmhlo::CompareOp>,
                    PointwiseToLinalgConverter<lmhlo::ComplexOp>,
@@ -933,7 +932,6 @@ void populateHLOToLinalgConversionPattern(MLIRContext* context,
                PointwiseToLinalgConverter<mhlo::AbsOp, false>,
                PointwiseToLinalgConverter<mhlo::AddOp, false>,
                PointwiseToLinalgConverter<mhlo::AndOp, false>,
-               PointwiseToLinalgConverter<mhlo::Atan2Op, false>,
                PointwiseToLinalgConverter<mhlo::CeilOp, false>,
                PointwiseToLinalgConverter<mhlo::CompareOp, false>,
                PointwiseToLinalgConverter<mhlo::ComplexOp, false>,
diff --git a/lib/Dialect/mhlo/transforms/transform_unranked_hlo.cc b/lib/Dialect/mhlo/transforms/transform_unranked_hlo.cc
index 7c01fa2..0be4c68 100644
--- a/lib/Dialect/mhlo/transforms/transform_unranked_hlo.cc
+++ b/lib/Dialect/mhlo/transforms/transform_unranked_hlo.cc
@@ -48,7 +48,7 @@ namespace {
 
 // TODO(herhut): Generate these out of op definitions.
 #define MAP_CHLO_OPERATION_CWISE_UNARY(fn, sep) \
-  fn(AcosOp) sep fn(AtanOp) sep fn(SinhOp) sep fn(TanOp)
+  fn(TanOp) sep fn(AcosOp) sep fn(SinhOp)
 
 template <typename OpTy>
 inline void AddLegalOpOnRankedTensor(ConversionTarget *target) {