diff --git a/mlir/lib/Dialect/Math/Transforms/PolynomialApproximation.cpp b/mlir/lib/Dialect/Math/Transforms/PolynomialApproximation.cpp
--- a/mlir/lib/Dialect/Math/Transforms/PolynomialApproximation.cpp
+++ b/mlir/lib/Dialect/Math/Transforms/PolynomialApproximation.cpp
@@ -209,8 +209,8 @@
   };
 
   // Clamp operand into [plusClamp, minusClamp] range.
-  Value minusClamp = bcast(f32Cst(builder, -7.9053111076354980f));
-  Value plusClamp = bcast(f32Cst(builder, 7.90531110763549805f));
+  Value minusClamp = bcast(f32Cst(builder, -7.99881172180175781f));
+  Value plusClamp = bcast(f32Cst(builder, 7.99881172180175781f));
   Value x = clamp(builder, op.operand(), minusClamp, plusClamp);
 
   // Mask for tiny values that are approximated with `operand`.
diff --git a/mlir/test/Dialect/Math/polynomial-approximation.mlir b/mlir/test/Dialect/Math/polynomial-approximation.mlir
--- a/mlir/test/Dialect/Math/polynomial-approximation.mlir
+++ b/mlir/test/Dialect/Math/polynomial-approximation.mlir
@@ -248,8 +248,8 @@
 
 // CHECK-LABEL:   func @tanh_scalar(
 // CHECK-SAME:                      %[[VAL_0:.*]]: f32) -> f32 {
-// CHECK:           %[[VAL_1:.*]] = arith.constant -7.90531111 : f32
-// CHECK:           %[[VAL_2:.*]] = arith.constant 7.90531111 : f32
+// CHECK:           %[[VAL_1:.*]] = arith.constant -7.99881172 : f32
+// CHECK:           %[[VAL_2:.*]] = arith.constant 7.99881172 : f32
 // CHECK:           %[[VAL_3:.*]] = arith.constant 4.000000e-04 : f32
 // CHECK:           %[[VAL_4:.*]] = arith.constant 0.00489352457 : f32
 // CHECK:           %[[VAL_5:.*]] = arith.constant 6.37261954E-4 : f32
@@ -290,7 +290,7 @@
 
 // CHECK-LABEL:   func @tanh_vector(
 // CHECK-SAME:                      %[[VAL_0:.*]]: vector<8xf32>) -> vector<8xf32> {
-// CHECK:           %[[VAL_1:.*]] = arith.constant dense<-7.90531111> : vector<8xf32>
+// CHECK:           %[[VAL_1:.*]] = arith.constant dense<-7.99881172> : vector<8xf32>
 // CHECK-NOT:       tanh
 // CHECK-COUNT-2:   select
 // CHECK:           %[[VAL_33:.*]] = select