diff --git a/mlir/include/mlir/Dialect/Math/IR/MathOps.td b/mlir/include/mlir/Dialect/Math/IR/MathOps.td
--- a/mlir/include/mlir/Dialect/Math/IR/MathOps.td
+++ b/mlir/include/mlir/Dialect/Math/IR/MathOps.td
@@ -482,6 +482,8 @@
     %a = math.floor %b : f64
     ```
   }];
+
+  let hasFolder = 1;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/mlir/lib/Dialect/Math/IR/MathOps.cpp b/mlir/lib/Dialect/Math/IR/MathOps.cpp
--- a/mlir/lib/Dialect/Math/IR/MathOps.cpp
+++ b/mlir/lib/Dialect/Math/IR/MathOps.cpp
@@ -427,6 +427,18 @@
   });
 }
 
+//===----------------------------------------------------------------------===//
+// FloorOp folder
+//===----------------------------------------------------------------------===//
+
+OpFoldResult math::FloorOp::fold(ArrayRef<Attribute> operands) {
+  return constFoldUnaryOp<FloatAttr>(operands, [](const APFloat &a) {
+    APFloat result(a);
+    result.roundToIntegral(llvm::RoundingMode::TowardNegative);
+    return result;
+  });
+}
+
 //===----------------------------------------------------------------------===//
 // RoundOp folder
 //===----------------------------------------------------------------------===//
diff --git a/mlir/test/Dialect/Math/canonicalize.mlir b/mlir/test/Dialect/Math/canonicalize.mlir
--- a/mlir/test/Dialect/Math/canonicalize.mlir
+++ b/mlir/test/Dialect/Math/canonicalize.mlir
@@ -411,3 +411,21 @@
   %0 = math.round %v1 : vector<4xf32>
   return %0 : vector<4xf32>
 }
+
+// CHECK-LABEL: @floor_fold
+// CHECK: %[[cst:.+]] = arith.constant 0.000000e+00 : f32
+// CHECK: return %[[cst]]
+func.func @floor_fold() -> f32 {
+  %c = arith.constant 0.3 : f32
+  %r = math.floor %c : f32
+  return %r : f32
+}
+
+// CHECK-LABEL: @floor_fold2
+// CHECK: %[[cst:.+]] = arith.constant 2.000000e+00 : f32
+// CHECK: return %[[cst]]
+func.func @floor_fold2() -> f32 {
+  %c = arith.constant 2.0 : f32
+  %r = math.floor %c : f32
+  return %r : f32
+}