diff --git a/mlir/include/mlir/Dialect/DXSA/IR/DXSAOps.td b/mlir/include/mlir/Dialect/DXSA/IR/DXSAOps.td
index 7d132f6865b5..24deb0fedcc4 100644
--- a/mlir/include/mlir/Dialect/DXSA/IR/DXSAOps.td
+++ b/mlir/include/mlir/Dialect/DXSA/IR/DXSAOps.td
@@ -281,6 +281,16 @@ def DXSA_ComponentMaskAttr :
   let assemblyFormat = "`<` $value `>`";
 }
 
+//===----------------------------------------------------------------------===//
+// DXSA attribute Constraints
+//===----------------------------------------------------------------------===//
+
+// This constraint does not treat the most significant bit as a sign bit,
+// so it is safe to use on unsigned integer attributes.
+def DXSA_UIntNonZero : AttrConstraint<
+    CPred<"!::llvm::cast<::mlir::IntegerAttr>($_self).getValue().isZero()">,
+    "whose value is non-zero">;
+
 //===----------------------------------------------------------------------===//
 // DXSA op definitions
 //===----------------------------------------------------------------------===//
@@ -790,4 +800,23 @@ def DXSA_DclHsMaxTessFactor : DXSA_Op<"dcl_hs_max_tessfactor"> {
   let hasVerifier = 1;
 }
 
+def DXSA_DclHsJoinPhaseInstanceCount :
+    DXSA_Op<"dcl_hs_join_phase_instance_count"> {
+  let summary = "declares the Join Phase instance count";
+  let description = [{
+    The `dxsa.dcl_hs_join_phase_instance_count` operation declares
+    the Join Phase instance count.
+
+    The `$count` must be a positive 32-bit unsigned integer in the range [1, 2^32 - 1].
+
+    Example:
+
+    ```mlir
+    dxsa.dcl_hs_join_phase_instance_count 42
+    ```
+  }];
+  let arguments = (ins ConfinedAttr<UI32Attr, [DXSA_UIntNonZero]>:$count);
+  let assemblyFormat = "$count attr-dict";
+}
+
 #endif // DXSA_OPS
diff --git a/mlir/lib/Target/DXSA/BinaryParser.cpp b/mlir/lib/Target/DXSA/BinaryParser.cpp
index 8cb113c31ef0..8464dba91296 100644
--- a/mlir/lib/Target/DXSA/BinaryParser.cpp
+++ b/mlir/lib/Target/DXSA/BinaryParser.cpp
@@ -659,6 +659,11 @@ class DXBuilder {
         builder, loc, builder.getF32FloatAttr(maxTessFactor));
   }
 
+  Instruction buildDclHsJoinPhaseInstanceCount(uint32_t count, Location loc) {
+    return dxsa::DclHsJoinPhaseInstanceCount::create(
+        builder, loc, builder.getUI32IntegerAttr(count));
+  }
+
 private:
   MLIRContext *context;
   ModuleOp module;
@@ -1229,6 +1234,12 @@ class Parser {
     return builder.buildDclHsMaxTessFactor(maxTessFactor, loc);
   }
 
+  FailureOr<Instruction> parseDclHsJoinPhaseInstanceCount(Location loc) {
+    auto count = parseToken();
+    FAILURE_IF_FAILED(count);
+    return builder.buildDclHsJoinPhaseInstanceCount(*count, loc);
+  }
+
   OptionalParseResult parseDclInstruction(uint32_t opcodeToken, Location loc,
                                           Instruction &out) {
     FailureOr<Instruction> result;
@@ -1287,6 +1298,9 @@ class Parser {
     case D3D11_SB_OPCODE_DCL_HS_MAX_TESSFACTOR:
       result = parseDclHsMaxTessFactor(loc);
       break;
+    case D3D11_SB_OPCODE_DCL_HS_JOIN_PHASE_INSTANCE_COUNT:
+      result = parseDclHsJoinPhaseInstanceCount(loc);
+      break;
     default:
       return std::nullopt;
     }
diff --git a/mlir/test/Target/DXSA/dcl_hs_join_phase_instance_count.mlir b/mlir/test/Target/DXSA/dcl_hs_join_phase_instance_count.mlir
new file mode 100644
index 000000000000..03e92f30645c
--- /dev/null
+++ b/mlir/test/Target/DXSA/dcl_hs_join_phase_instance_count.mlir
@@ -0,0 +1,5 @@
+// RUN: mlir-translate --import-dxsa-bin %S/inputs/dcl_hs_join_phase_instance_count.bin | FileCheck %s
+
+// CHECK:      module {
+// CHECK-NEXT:   dxsa.dcl_hs_join_phase_instance_count 42
+// CHECK-NEXT: }
diff --git a/mlir/test/Target/DXSA/dcl_hs_join_phase_instance_count_invalid.mlir b/mlir/test/Target/DXSA/dcl_hs_join_phase_instance_count_invalid.mlir
new file mode 100644
index 000000000000..ac29a37a687e
--- /dev/null
+++ b/mlir/test/Target/DXSA/dcl_hs_join_phase_instance_count_invalid.mlir
@@ -0,0 +1,14 @@
+// RUN: mlir-opt %s -split-input-file -verify-diagnostics
+
+// expected-error@+1 {{attribute 'count' failed to satisfy constraint: 32-bit unsigned integer attribute whose value is non-zero}}
+dxsa.dcl_hs_join_phase_instance_count 0
+
+// -----
+
+// expected-error@+1 {{negative integer literal not valid for unsigned integer type}}
+dxsa.dcl_hs_join_phase_instance_count -1
+
+// -----
+
+// expected-error@+1 {{integer constant out of range for attribute}}
+dxsa.dcl_hs_join_phase_instance_count 4294967296
diff --git a/mlir/test/Target/DXSA/inputs/dcl_hs_join_phase_instance_count.bin b/mlir/test/Target/DXSA/inputs/dcl_hs_join_phase_instance_count.bin
new file mode 100644
index 000000000000..36d20ab5732c
Binary files /dev/null and b/mlir/test/Target/DXSA/inputs/dcl_hs_join_phase_instance_count.bin differ