diff --git a/mlir/include/mlir/Dialect/Shape/IR/Shape.h b/mlir/include/mlir/Dialect/Shape/IR/Shape.h
--- a/mlir/include/mlir/Dialect/Shape/IR/Shape.h
+++ b/mlir/include/mlir/Dialect/Shape/IR/Shape.h
@@ -17,6 +17,7 @@
 #include "mlir/IR/Dialect.h"
 #include "mlir/IR/OpDefinition.h"
 #include "mlir/IR/OpImplementation.h"
+#include "mlir/Interfaces/ControlFlowInterfaces.h"
 #include "mlir/Interfaces/InferTypeOpInterface.h"
 #include "mlir/Interfaces/SideEffectInterfaces.h"
 
diff --git a/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td b/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
--- a/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
+++ b/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
@@ -14,6 +14,7 @@
 #define SHAPE_OPS
 
 include "mlir/Dialect/Shape/IR/ShapeBase.td"
+include "mlir/Interfaces/ControlFlowInterfaces.td"
 include "mlir/Interfaces/InferTypeOpInterface.td"
 include "mlir/Interfaces/SideEffectInterfaces.td"
 
@@ -426,12 +427,16 @@
     nothing else. They should not exist after a program is fully lowered and
     ready to execute.
   }];
-  let arguments = (ins Shape_WitnessType);
-  let regions = (region SizedRegion<1>:$thenRegion);
+  let arguments = (ins Shape_WitnessType:$witness);
+  let regions = (region SizedRegion<1>:$doRegion);
   let results = (outs Variadic<AnyType>:$results);
+
+  let printer = [{ return ::print(p, *this); }];
+  let parser = [{ return ::parse$cppClass(parser, result); }];
 }
 
-def Shape_AssumingYieldOp : Shape_Op<"assuming_yield", [Terminator]> {
+def Shape_AssumingYieldOp : Shape_Op<"assuming_yield",
+                                     [NoSideEffect, ReturnLike, Terminator]> {
   let summary = "Yield operation";
   let description = [{
     This yield operation represents a return operation within the assert_and_exec
@@ -441,6 +446,11 @@
   }];
 
   let arguments = (ins Variadic<AnyType>:$operands);
+
+  let builders = [
+    OpBuilder<"OpBuilder &builder, OperationState &result",
+    [{ /* nothing to do */ }]>
+  ];
 }
 
 def Shape_CstrBroadcastableOp : Shape_Op<"cstr_broadcastable", []> {
diff --git a/mlir/lib/Dialect/Shape/CMakeLists.txt b/mlir/lib/Dialect/Shape/CMakeLists.txt
--- a/mlir/lib/Dialect/Shape/CMakeLists.txt
+++ b/mlir/lib/Dialect/Shape/CMakeLists.txt
@@ -8,6 +8,7 @@
   MLIRShapeOpsIncGen
 
   LINK_LIBS PUBLIC
+  MLIRControlFlowInterfaces
   MLIRDialect
   MLIRInferTypeOpInterface
   MLIRIR
diff --git a/mlir/lib/Dialect/Shape/IR/Shape.cpp b/mlir/lib/Dialect/Shape/IR/Shape.cpp
--- a/mlir/lib/Dialect/Shape/IR/Shape.cpp
+++ b/mlir/lib/Dialect/Shape/IR/Shape.cpp
@@ -108,6 +108,50 @@
 }
 
 //===----------------------------------------------------------------------===//
+// AssumingOp
+//===----------------------------------------------------------------------===//
+
+static ParseResult parseAssumingOp(OpAsmParser &parser,
+                                   OperationState &result) {
+  result.regions.reserve(1);
+  Region *doRegion = result.addRegion();
+
+  auto &builder = parser.getBuilder();
+  OpAsmParser::OperandType cond;
+  if (parser.parseOperand(cond) ||
+      parser.resolveOperand(cond, builder.getType<WitnessType>(),
+                            result.operands))
+    return failure();
+
+  // Parse optional results type list.
+  if (parser.parseOptionalArrowTypeList(result.types))
+    return failure();
+
+  // Parse the region and add a terminator if elided.
+  if (parser.parseRegion(*doRegion, /*arguments=*/{}, /*argTypes=*/{}))
+    return failure();
+  AssumingOp::ensureTerminator(*doRegion, parser.getBuilder(), result.location);
+
+  // Parse the optional attribute list.
+  if (parser.parseOptionalAttrDict(result.attributes))
+    return failure();
+  return success();
+}
+
+static void print(OpAsmPrinter &p, AssumingOp op) {
+  bool yieldsResults = !op.results().empty();
+
+  p << AssumingOp::getOperationName() << " " << op.witness();
+  if (yieldsResults) {
+    p << " -> (" << op.getResultTypes() << ")";
+  }
+  p.printRegion(op.doRegion(),
+                /*printEntryBlockArgs=*/false,
+                /*printBlockTerminators=*/yieldsResults);
+  p.printOptionalAttrDict(op.getAttrs());
+}
+
+//===----------------------------------------------------------------------===//
 // BroadcastOp
 //===----------------------------------------------------------------------===//
 
diff --git a/mlir/test/Dialect/Shape/ops.mlir b/mlir/test/Dialect/Shape/ops.mlir
--- a/mlir/test/Dialect/Shape/ops.mlir
+++ b/mlir/test/Dialect/Shape/ops.mlir
@@ -74,9 +74,9 @@
   %w0 = "shape.cstr_broadcastable"(%0, %1) : (!shape.shape, !shape.shape) -> !shape.witness
   %w1 = "shape.cstr_eq"(%0, %1) : (!shape.shape, !shape.shape) -> !shape.witness
   %w3 = "shape.assuming_all"(%w0, %w1) : (!shape.witness, !shape.witness) -> !shape.witness
-  "shape.assuming"(%w3) ( {
+  shape.assuming %w3 -> !shape.shape {
     %2 = "shape.any"(%0, %1)  : (!shape.shape, !shape.shape) -> !shape.shape
     "shape.assuming_yield"(%2) : (!shape.shape) -> ()
-  }) : (!shape.witness) -> !shape.shape
+  }
   return
 }