diff --git a/docs/ReleaseNotes.md b/docs/ReleaseNotes.md
index d426b955f2..609fd82f15 100644
--- a/docs/ReleaseNotes.md
+++ b/docs/ReleaseNotes.md
@@ -39,6 +39,7 @@ line upon naming the release. Refer to previous for appropriate section names.
 
 #### Other Changes
 - Fixed mesh shader semantics that were incorrectly case sensitive.
+- DXIL validation now rejects non-standard integer bit widths (e.g. `i25`) in instructions.
 
 ### Version 1.9.2602
 
diff --git a/lib/DxilValidation/DxilValidation.cpp b/lib/DxilValidation/DxilValidation.cpp
index 2236dd11f7..e8eb2b9c74 100644
--- a/lib/DxilValidation/DxilValidation.cpp
+++ b/lib/DxilValidation/DxilValidation.cpp
@@ -2659,6 +2659,19 @@ static bool IsDxilBuiltinStructType(StructType *ST, hlsl::OP *HlslOP) {
   }
 }
 
+static bool IsValidIntBitWidth(unsigned Width) {
+  switch (Width) {
+  case 1:
+  case 8:
+  case 16:
+  case 32:
+  case 64:
+    return true;
+  default:
+    return false;
+  }
+}
+
 // outer type may be: [ptr to][1 dim array of]( UDT struct | scalar )
 // inner type (UDT struct member) may be: [N dim array of]( UDT struct | scalar
 // ) scalar type may be: ( float(16|32|64) | int(16|32|64) )
@@ -2717,8 +2730,7 @@ static bool ValidateType(Type *Ty, ValidationContext &ValCtx,
     return true;
   }
   if (Ty->isIntegerTy()) {
-    unsigned Width = Ty->getIntegerBitWidth();
-    if (Width != 1 && Width != 8 && Width != 16 && Width != 32 && Width != 64) {
+    if (!IsValidIntBitWidth(Ty->getIntegerBitWidth())) {
       ValCtx.EmitTypeError(Ty, ValidationRule::TypesIntWidth);
       return false;
     }
@@ -3388,10 +3400,13 @@ static void ValidateFunctionBody(Function *F, ValidationContext &ValCtx) {
           }
         }
         if (IntegerType *IT = dyn_cast<IntegerType>(op->getType())) {
-          if (IT->getBitWidth() == 8) {
+          unsigned BW = IT->getBitWidth();
+          if (BW == 8) {
             // We always fail if we see i8 as operand type of a non-lifetime
             // instruction.
             ValCtx.EmitInstrError(&I, ValidationRule::TypesI8);
+          } else {
+            ValidateType(IT, ValCtx);
           }
         }
       }
@@ -3402,12 +3417,15 @@ static void ValidateFunctionBody(Function *F, ValidationContext &ValCtx) {
       while (isa<ArrayType>(Ty))
         Ty = Ty->getArrayElementType();
       if (IntegerType *IT = dyn_cast<IntegerType>(Ty)) {
-        if (IT->getBitWidth() == 8) {
+        unsigned BW = IT->getBitWidth();
+        if (BW == 8) {
           // Allow i8* cast for llvm.lifetime.* intrinsics.
           if (!SupportsLifetimeIntrinsics || !isa<BitCastInst>(I) ||
               !onlyUsedByLifetimeMarkers(&I)) {
             ValCtx.EmitInstrError(&I, ValidationRule::TypesI8);
           }
+        } else {
+          ValidateType(IT, ValCtx);
         }
       }
 
diff --git a/tools/clang/test/LitDXILValidation/int-width-validation.ll b/tools/clang/test/LitDXILValidation/int-width-validation.ll
new file mode 100644
index 0000000000..e1ee2c975f
--- /dev/null
+++ b/tools/clang/test/LitDXILValidation/int-width-validation.ll
@@ -0,0 +1,35 @@
+; RUN: not %dxv %s 2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i1:32-i8:32-i16:32-i32:32-i64:64-f16:32-f32:32-f64:64-n8:16:32:64"
+target triple = "dxil-ms-dx"
+
+; CHECK: Int type 'i25' has an invalid width.
+; CHECK: Int type 'i25' has an invalid width.
+; CHECK: Validation failed.
+
+define void @main() {
+  ; Test invalid int width in operand and result types.
+  %1 = add i25 0, 1
+  ; Test invalid int width inside array result type.
+  %2 = select i1 true, [2 x i25] zeroinitializer, [2 x i25] zeroinitializer
+  call void @dx.op.storeOutput.f32(i32 5, i32 0, i32 0, i8 0, float 0.000000e+00)
+  ret void
+}
+
+declare void @dx.op.storeOutput.f32(i32, i32, i32, i8, float) #0
+
+attributes #0 = { nounwind }
+
+!dx.version = !{!0}
+!dx.valver = !{!0}
+!dx.shaderModel = !{!1}
+!dx.entryPoints = !{!2}
+
+!0 = !{i32 1, i32 0}
+!1 = !{!"ps", i32 6, i32 0}
+!2 = !{void ()* @main, !"main", !3, null, null}
+!3 = !{null, !4, null}
+!4 = !{!5}
+!5 = !{i32 0, !"SV_Target", i8 9, i8 16, !6, i8 0, i32 1, i8 1, i32 0, i8 0, !7}
+!6 = !{i32 0}
+!7 = !{i32 3, i32 1}