Index: llvm/lib/Transforms/Scalar/SROA.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/SROA.cpp
+++ llvm/lib/Transforms/Scalar/SROA.cpp
@@ -2811,10 +2811,11 @@
       if (BeginOffset > NewAllocaBeginOffset ||
           EndOffset < NewAllocaEndOffset)
         return false;
+      // Length must be in range for FixedVectorType.
       auto *C = cast<ConstantInt>(II.getLength());
-      if (C->getBitWidth() > 64)
+      const uint64_t Len = C->getLimitedValue();
+      if (Len > std::numeric_limits<unsigned>::max())
         return false;
-      const auto Len = C->getZExtValue();
       auto *Int8Ty = IntegerType::getInt8Ty(NewAI.getContext());
       auto *SrcTy = FixedVectorType::get(Int8Ty, Len);
       return canConvertValue(DL, SrcTy, AllocaTy) &&
Index: llvm/test/Transforms/SROA/slice-width.ll
===================================================================
--- llvm/test/Transforms/SROA/slice-width.ll
+++ llvm/test/Transforms/SROA/slice-width.ll
@@ -145,3 +145,16 @@
   call void @llvm.memset.p0i8.i64(i8* align 16 %array, i8 0, i64 ptrtoint (void ()* @PR50888 to i64), i1 false)
   ret void
 }
+
+; Don't crash on out-of-bounds length.
+
+define void @PR50910() {
+; CHECK-LABEL: @PR50910(
+; CHECK-NEXT:    [[T1:%.*]] = alloca i8, i64 1, align 8
+; CHECK-NEXT:    call void @llvm.memset.p0i8.i64(i8* align 8 [[T1]], i8 0, i64 1, i1 false)
+; CHECK-NEXT:    ret void
+;
+  %t1 = alloca i8, i64 1, align 8
+  call void @llvm.memset.p0i8.i64(i8* align 8 %t1, i8 0, i64 4294967296, i1 false)
+  ret void
+}