diff --git a/lib/DXIL/DxilOperations.cpp b/lib/DXIL/DxilOperations.cpp
index ddd3279cf9..b3b3aea49f 100644
--- a/lib/DXIL/DxilOperations.cpp
+++ b/lib/DXIL/DxilOperations.cpp
@@ -3564,8 +3564,14 @@ void OP::UpdateCache(OpCodeClass opClass, Type *Ty, llvm::Function *F) {
 Function *OP::GetOpFunc(OpCode opCode, Type *pOverloadType) {
   if (opCode == OpCode::NumOpCodes)
     return nullptr;
-  if (!IsOverloadLegal(opCode, pOverloadType))
+  if (!pOverloadType)
     return nullptr;
+  // Illegal overloads are generated and eliminated by DXIL op constant
+  // evaluation for a number of cases where a double overload of an HL intrinsic
+  // that otherwise does not support double is used for literal values, when
+  // there is no constant evaluation for the intrinsic in CodeGen.
+  // Illegal overloads of DXIL intrinsics may survive through to final DXIL,
+  // but these will be caught by the validator, and this is not a regression.
 
   OpCodeClass opClass = m_OpCodeProps[(unsigned)opCode].opCodeClass;
   Function *&F =
diff --git a/tools/clang/test/CodeGenDXIL/literal/fmod_const_eval.hlsl b/tools/clang/test/CodeGenDXIL/literal/fmod_const_eval.hlsl
new file mode 100644
index 0000000000..bff10c2a2e
--- /dev/null
+++ b/tools/clang/test/CodeGenDXIL/literal/fmod_const_eval.hlsl
@@ -0,0 +1,62 @@
+// RUN: %dxc -T vs_6_0 %s -E main | FileCheck %s
+// RUN: not %dxc -T vs_6_0 %s -E main -DNO_FOLD 2>&1 | FileCheck %s --check-prefixes=NO_FOLD
+
+// The code path generates invalid overload.  The invalid overload will either be
+// constant folded away, or caught by the validator.
+
+// Ensure fmod is constant evaluated during codegen, or dxil const eval
+// TODO: handle fp specials properly, tracked with https://github.com/microsoft/DirectXShaderCompiler/issues/6567
+
+
+RWBuffer<float4> results : register(u0);
+
+[shader("vertex")]
+void main(bool b : B) {
+    uint i = 0;
+
+    // Literal float
+    // 2.5, -2.5, 2.5, -2.5
+    // CHECK: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 0, i32 undef, float 2.500000e+00, float -2.500000e+00, float 2.500000e+00, float -2.500000e+00, i8 15)
+    results[i++] = float4(fmod(5.5, 3.0),
+                          fmod(-5.5, 3.0),
+                          fmod(5.5, -3.0),
+                          fmod(-5.5, -3.0));
+
+    // Explicit float
+    // 2.5, -2.5, 2.5, -2.5
+    // CHECK: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 1, i32 undef, float 2.500000e+00, float -2.500000e+00, float 2.500000e+00, float -2.500000e+00, i8 15)
+    results[i++] = float4(fmod(5.5f, 3.0f),
+                          fmod(-5.5f, 3.0f),
+                          fmod(5.5f, -3.0f),
+                          fmod(-5.5f, -3.0f));
+
+#ifdef SPECIALS
+    // Literal float
+	// 0.0, -0.0, NaN, -NaN
+	// SPECIALS: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 2, i32 undef, float 0.000000e+00, -0.000000e+00, float 0x7FF8000000000000, float 0x7FF8000000000000, i8 15)
+	results[i++] = float4(fmod(0.0, 1.0),
+	                      fmod(-0.0, 1.0),
+						  fmod(5.5, 0.0),
+						  fmod(-5.5, 0.0));
+
+	// Explicit float
+	// 0.0, -0.0, NaN, -NaN
+    // SPECIALS: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 3, i32 undef, float 0.000000e+00, -0.000000e+00, float 0x7FF8000000000000, float 0x7FF8000000000000, i8 15)
+	results[i++] = float4(fmod(0.0f, 1.0f),
+	                      fmod(-0.0f, 1.0f),
+						  fmod(5.5f, 0.0f),
+						  fmod(-5.5f, 0.0f));
+
+#endif // SPECIALS
+
+#ifdef NO_FOLD
+    // Currently, we rely on constant folding of DXIL ops to get rid of illegal
+    // double overloads. If this doesn't happen, we expect a validation error.
+    // Ternary operator can return literal type, while not being foldable due
+    // non-constant condition.
+    // NO_FOLD: error: validation errors
+    // NO_FOLD: error: DXIL intrinsic overload must be valid.
+    float result = fmod(-5.5, b ? 1.5 : 0.5);
+    results[i++] = float4(result, 0, 0, 0);
+#endif // NO_FOLD
+}
diff --git a/tools/clang/test/CodeGenDXIL/literal/length_const_eval.hlsl b/tools/clang/test/CodeGenDXIL/literal/length_const_eval.hlsl
new file mode 100644
index 0000000000..4e6fbec23f
--- /dev/null
+++ b/tools/clang/test/CodeGenDXIL/literal/length_const_eval.hlsl
@@ -0,0 +1,40 @@
+// RUN: %dxc -T vs_6_0 %s -E main | FileCheck %s
+// RUN: not %dxc -T vs_6_0 %s -E main -DNO_FOLD 2>&1 | FileCheck %s --check-prefixes=NO_FOLD
+
+// The code path generates invalid overload.  The invalid overload will either be
+// constant folded away, or caught by the validator.
+
+// Ensure length is constant evaluated during codegen, or dxil const eval
+// TODO: handle fp specials properly, tracked with https://github.com/microsoft/DirectXShaderCompiler/issues/6567
+
+RWBuffer<float4> results : register(u0);
+
+[shader("vertex")]
+void main(bool b : B) {
+    uint i = 0;
+
+    // Literal float
+    // CHECK: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 0, i32 undef, float 0x3FE6A09E60000000, float 0x4004C8DC20000000, float 0.000000e+00, float 0.000000e+00, i8 15)
+    results[i++] = float4(length(0.5.xx),
+                          length(-1.5.xxx),
+                          length(0.0.xxxx),
+                          length(-0.0.xxxx));
+
+    // Explicit float
+    // CHECK: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 1, i32 undef, float 0x3FE6A09E60000000, float 0x4004C8DC20000000, float 0.000000e+00, float 0.000000e+00, i8 15)
+    results[i++] = float4(length(0.5F.xx),
+                          length(-1.5F.xxx),
+                          length(0.0F.xxxx),
+                          length(-0.0F.xxxx));
+
+#ifdef NO_FOLD
+    // Currently, we rely on constant folding of DXIL ops to get rid of illegal
+    // double overloads. If this doesn't happen, we expect a validation error.
+    // Ternary operator can return literal type, while not being foldable due
+    // non-constant condition.
+    // NO_FOLD: error: validation errors
+    // NO_FOLD: error: DXIL intrinsic overload must be valid.
+    float result = length((b ? 1.5 : 0.5).xxx);
+    results[i++] = float4(result, 0, 0, 0);
+#endif // NO_FOLD
+}
diff --git a/tools/clang/test/CodeGenDXIL/literal/normalize_const_eval.hlsl b/tools/clang/test/CodeGenDXIL/literal/normalize_const_eval.hlsl
new file mode 100644
index 0000000000..280bd30465
--- /dev/null
+++ b/tools/clang/test/CodeGenDXIL/literal/normalize_const_eval.hlsl
@@ -0,0 +1,40 @@
+// RUN: %dxc -T vs_6_0 %s -E main | FileCheck %s
+// RUN: not %dxc -T vs_6_0 %s -E main -DNO_FOLD 2>&1 | FileCheck %s --check-prefixes=NO_FOLD
+
+// The code path generates invalid overload.  The invalid overload will either be
+// constant folded away, or caught by the validator.
+
+// Ensure normalize is constant evaluated during codegen, or dxil const eval
+// TODO: handle fp specials properly, tracked with https://github.com/microsoft/DirectXShaderCompiler/issues/6567
+
+
+RWBuffer<float4> results : register(u0);
+
+[shader("vertex")]
+void main(bool b : B) {
+    uint i = 0;
+
+    // Literal float
+    // CHECK: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 0, i32 undef, float 0x3FE6A09E60000000, float 0xBFE279A740000000, float 0x7FF8000000000000, float 0x7FF8000000000000, i8 15)
+    results[i++] = float4(normalize(0.5.xx).x,
+                          normalize(-1.5.xxx).x,
+                          normalize(0.0.xxxx).x,
+                          normalize(-0.0.xxxx).x);
+
+    // Explicit float
+    // CHECK: call void @dx.op.bufferStore.f32(i32 69, %dx.types.Handle %{{.+}}, i32 1, i32 undef, float 0x3FE6A09E60000000, float 0xBFE279A740000000, float 0x7FF8000000000000, float 0x7FF8000000000000, i8 15)
+    results[i++] = float4(normalize(0.5F.xx).x,
+                          normalize(-1.5F.xxx).x,
+                          normalize(0.0F.xxxx).x,
+                          normalize(-0.0F.xxxx).x);
+
+#ifdef NO_FOLD
+    // Currently, we rely on constant folding of DXIL ops to get rid of illegal
+    // double overloads. If this doesn't happen, we expect a validation error.
+    // Ternary operator can return literal type, while not being foldable due
+    // non-constant condition.
+    // NO_FOLD: error: validation errors
+    // NO_FOLD: error: DXIL intrinsic overload must be valid.
+    results[i++] = normalize((b ? 1.25 : 2.5).xxxx);
+#endif // NO_FOLD
+}