diff --git a/lib/HLSL/HLOperationLower.cpp b/lib/HLSL/HLOperationLower.cpp
index 4f22a4598d..84d0c5b36a 100644
--- a/lib/HLSL/HLOperationLower.cpp
+++ b/lib/HLSL/HLOperationLower.cpp
@@ -2590,6 +2590,13 @@ Value *ExpandDot(Value *arg0, Value *arg1, unsigned vecSize, hlsl::OP *hlslOP,
 
 Value *TranslateFDot(Value *arg0, Value *arg1, unsigned vecSize,
                      hlsl::OP *hlslOP, IRBuilder<> &Builder) {
+  // Dot2/3/4 DXIL operations only support half and float, not double.
+  // For double vectors, expand the dot product using FMul and FMad.
+  if (arg0->getType()->getScalarType()->isDoubleTy()) {
+    return ExpandDot(arg0, arg1, vecSize, hlslOP, Builder,
+                     DXIL::OpCode::FMad);
+  }
+
   switch (vecSize) {
   case 2:
     return TrivialDotOperation(OP::OpCode::Dot2, arg0, arg1, hlslOP, Builder);
diff --git a/tools/clang/test/HLSLFileCheck/hlsl/intrinsics/mul/mul_double.hlsl b/tools/clang/test/HLSLFileCheck/hlsl/intrinsics/mul/mul_double.hlsl
new file mode 100644
index 0000000000..f4f33487ca
--- /dev/null
+++ b/tools/clang/test/HLSLFileCheck/hlsl/intrinsics/mul/mul_double.hlsl
@@ -0,0 +1,33 @@
+// RUN: %dxc -T cs_6_0 -E main -DFUNC=mul -DDIM=4 %s  | FileCheck %s
+// RUN: %dxc -T cs_6_0 -E main -DFUNC=mul -DDIM=3 %s  | FileCheck %s
+// RUN: %dxc -T cs_6_0 -E main -DFUNC=mul -DDIM=2 %s  | FileCheck %s
+// RUN: %dxc -T cs_6_0 -E main -DFUNC=dot -DDIM=4 %s  | FileCheck %s
+// RUN: %dxc -T cs_6_0 -E main -DFUNC=dot -DDIM=3 %s  | FileCheck %s
+// RUN: %dxc -T cs_6_0 -E main -DFUNC=dot -DDIM=2 %s  | FileCheck %s
+
+// Verify that mul and dot of double vectors do not produce invalid DXIL Dot
+// intrinsics (Dot2/3/4 only support half and float). Instead, the dot product
+// should be expanded using FMul and FMad.
+// %dxc runs validation, so the test implicitly verifies DXIL validity.
+
+// CHECK-NOT: call double @dx.op.dot2.f64
+// CHECK-NOT: call double @dx.op.dot3.f64
+// CHECK-NOT: call double @dx.op.dot4.f64
+// CHECK: fmul fast double
+// CHECK: call double @dx.op.tertiary.f64(i32 46,
+
+#if DIM == 4
+typedef double4 DVec;
+#elif DIM == 3
+typedef double3 DVec;
+#else
+typedef double2 DVec;
+#endif
+
+RWStructuredBuffer<DVec> In;
+RWStructuredBuffer<double> Out;
+
+[numthreads(1, 1, 1)]
+void main() {
+    Out[0] = FUNC(In[0], In[1]);
+}