diff --git a/source/fuzz/force_render_red.cpp b/source/fuzz/force_render_red.cpp
index ed60bd0..fd0587a 100644
--- a/source/fuzz/force_render_red.cpp
+++ b/source/fuzz/force_render_red.cpp
@@ -212,7 +212,6 @@
     auto new_exit_block = MakeUnique<opt::BasicBlock>(std::move(label));
     new_exit_block->AddInstruction(MakeUnique<opt::Instruction>(
         ir_context.get(), SpvOpReturn, 0, 0, opt::Instruction::OperandList()));
-    new_exit_block->SetParent(entry_point_function);
     entry_point_function->AddBasicBlock(std::move(new_exit_block));
   }
 
diff --git a/source/fuzz/transformation_add_dead_block.cpp b/source/fuzz/transformation_add_dead_block.cpp
index 3d77a80..5dce356 100644
--- a/source/fuzz/transformation_add_dead_block.cpp
+++ b/source/fuzz/transformation_add_dead_block.cpp
@@ -153,7 +153,6 @@
                                     : successor_block_id}}});
 
   // Add the new block to the enclosing function.
-  new_block->SetParent(enclosing_function);
   enclosing_function->InsertBasicBlockAfter(std::move(new_block),
                                             existing_block);
 
diff --git a/source/fuzz/transformation_add_early_terminator_wrapper.cpp b/source/fuzz/transformation_add_early_terminator_wrapper.cpp
index 0aa1214..9f86070 100644
--- a/source/fuzz/transformation_add_early_terminator_wrapper.cpp
+++ b/source/fuzz/transformation_add_early_terminator_wrapper.cpp
@@ -84,7 +84,6 @@
 
   // Add the basic block to the function as the sole block, and add the function
   // to the module.
-  basic_block->SetParent(function.get());
   function->AddBasicBlock(std::move(basic_block));
   function->SetFunctionEnd(MakeUnique<opt::Instruction>(
       ir_context, SpvOpFunctionEnd, 0, 0, opt::Instruction::OperandList()));
diff --git a/source/fuzz/transformation_add_function.cpp b/source/fuzz/transformation_add_function.cpp
index 214f741..9799373 100644
--- a/source/fuzz/transformation_add_function.cpp
+++ b/source/fuzz/transformation_add_function.cpp
@@ -276,12 +276,10 @@
     // Invariant: we should always be at a label instruction at this point.
     assert(message_.instruction(instruction_index).opcode() == SpvOpLabel);
 
-    // Make a basic block using the label instruction, with the new function
-    // as its parent.
+    // Make a basic block using the label instruction.
     std::unique_ptr<opt::BasicBlock> block =
         MakeUnique<opt::BasicBlock>(InstructionFromMessage(
             ir_context, message_.instruction(instruction_index)));
-    block->SetParent(new_function.get());
 
     // Consider successive instructions until we hit another label or the end
     // of the function, adding each such instruction to the block.
diff --git a/source/fuzz/transformation_inline_function.cpp b/source/fuzz/transformation_inline_function.cpp
index f58b123..f997491 100644
--- a/source/fuzz/transformation_inline_function.cpp
+++ b/source/fuzz/transformation_inline_function.cpp
@@ -183,7 +183,6 @@
     auto* cloned_block = block.Clone(ir_context);
     cloned_block = caller_function->InsertBasicBlockBefore(
         std::unique_ptr<opt::BasicBlock>(cloned_block), successor_block);
-    cloned_block->SetParent(caller_function);
     cloned_block->GetLabel()->SetResultId(result_id_map.at(cloned_block->id()));
     fuzzerutil::UpdateModuleIdBound(ir_context, cloned_block->id());
 
diff --git a/source/fuzz/transformation_merge_function_returns.cpp b/source/fuzz/transformation_merge_function_returns.cpp
index 90578a2..c7cb557 100644
--- a/source/fuzz/transformation_merge_function_returns.cpp
+++ b/source/fuzz/transformation_merge_function_returns.cpp
@@ -579,7 +579,6 @@
   }
 
   // Insert the new return block at the end of the function.
-  outer_return_block->SetParent(function);
   function->AddBasicBlock(std::move(outer_return_block));
 
   // All analyses must be invalidated because the structure of the module was
diff --git a/source/fuzz/transformation_outline_function.cpp b/source/fuzz/transformation_outline_function.cpp
index 26f9e0b..643fd69 100644
--- a/source/fuzz/transformation_outline_function.cpp
+++ b/source/fuzz/transformation_outline_function.cpp
@@ -778,7 +778,6 @@
       MakeUnique<opt::BasicBlock>(MakeUnique<opt::Instruction>(
           ir_context, SpvOpLabel, 0, message_.new_function_region_entry_block(),
           opt::Instruction::OperandList()));
-  outlined_region_entry_block->SetParent(outlined_function);
 
   if (&original_region_entry_block == &original_region_exit_block) {
     outlined_region_exit_block = outlined_region_entry_block.get();
@@ -815,8 +814,6 @@
       outlined_region_exit_block = cloned_block.get();
     }
 
-    cloned_block->SetParent(outlined_function);
-
     // Redirect any OpPhi operands whose predecessors are the original region
     // entry block to become the new function entry block.
     cloned_block->ForEachPhiInst([this](opt::Instruction* phi_inst) {
diff --git a/source/opt/basic_block.cpp b/source/opt/basic_block.cpp
index 3608448..b7e122c 100644
--- a/source/opt/basic_block.cpp
+++ b/source/opt/basic_block.cpp
@@ -248,7 +248,8 @@
   function_->InsertBasicBlockAfter(std::move(new_block_temp), this);
 
   new_block->insts_.Splice(new_block->end(), &insts_, iter, end());
-  new_block->SetParent(GetParent());
+  assert(new_block->GetParent() == GetParent() &&
+         "The parent should already be set appropriately.");
 
   context->AnalyzeDefUse(new_block->GetLabelInst());
 
diff --git a/source/opt/eliminate_dead_members_pass.cpp b/source/opt/eliminate_dead_members_pass.cpp
index 5b8f4ec..ab28932 100644
--- a/source/opt/eliminate_dead_members_pass.cpp
+++ b/source/opt/eliminate_dead_members_pass.cpp
@@ -20,7 +20,7 @@
 namespace {
 const uint32_t kRemovedMember = 0xFFFFFFFF;
 const uint32_t kSpecConstOpOpcodeIdx = 0;
-}
+}  // namespace
 
 namespace spvtools {
 namespace opt {
diff --git a/source/opt/function.cpp b/source/opt/function.cpp
index 52054ea..38c6695 100644
--- a/source/opt/function.cpp
+++ b/source/opt/function.cpp
@@ -42,7 +42,6 @@
   clone->blocks_.reserve(blocks_.size());
   for (const auto& b : blocks_) {
     std::unique_ptr<BasicBlock> bb(b->Clone(ctx));
-    bb->SetParent(clone);
     clone->AddBasicBlock(std::move(bb));
   }
 
diff --git a/source/opt/function.h b/source/opt/function.h
index 4b20dcb..9e1c727 100644
--- a/source/opt/function.h
+++ b/source/opt/function.h
@@ -213,6 +213,7 @@
 
 inline void Function::AddBasicBlock(std::unique_ptr<BasicBlock> b,
                                     iterator ip) {
+  b->SetParent(this);
   ip.InsertBefore(std::move(b));
 }
 
diff --git a/source/opt/inst_buff_addr_check_pass.cpp b/source/opt/inst_buff_addr_check_pass.cpp
index fa6c2c6..06acc7e 100644
--- a/source/opt/inst_buff_addr_check_pass.cpp
+++ b/source/opt/inst_buff_addr_check_pass.cpp
@@ -202,7 +202,6 @@
     (void)builder.AddInstruction(MakeUnique<Instruction>(
         context(), SpvOpBranch, 0, 0,
         std::initializer_list<Operand>{{SPV_OPERAND_TYPE_ID, {hdr_blk_id}}}));
-    first_blk_ptr->SetParent(&*input_func);
     input_func->AddBasicBlock(std::move(first_blk_ptr));
     // Linear search loop header block
     // TODO(greg-lunarg): Implement binary search
@@ -246,7 +245,6 @@
     (void)builder.AddInstruction(MakeUnique<Instruction>(
         context(), SpvOpBranch, 0, 0,
         std::initializer_list<Operand>{{SPV_OPERAND_TYPE_ID, {cont_blk_id}}}));
-    hdr_blk_ptr->SetParent(&*input_func);
     input_func->AddBasicBlock(std::move(hdr_blk_ptr));
     // Continue/Work Block. Read next buffer pointer and break if greater
     // than ref_ptr arg.
@@ -272,7 +270,6 @@
     (void)builder.AddConditionalBranch(uptr_test_inst->result_id(),
                                        bound_test_blk_id, hdr_blk_id,
                                        kInvalidId, SpvSelectionControlMaskNone);
-    cont_blk_ptr->SetParent(&*input_func);
     input_func->AddBasicBlock(std::move(cont_blk_ptr));
     // Bounds test block. Read length of selected buffer and test that
     // all len arg bytes are in buffer.
@@ -333,7 +330,6 @@
         std::initializer_list<Operand>{
             {SPV_OPERAND_TYPE_ID, {len_test_inst->result_id()}}}));
     // Close block
-    bound_test_blk_ptr->SetParent(&*input_func);
     input_func->AddBasicBlock(std::move(bound_test_blk_ptr));
     // Close function and add function to module
     std::unique_ptr<Instruction> func_end_inst(
diff --git a/source/opt/instrument_pass.cpp b/source/opt/instrument_pass.cpp
index e7d9778..ed34fb0 100644
--- a/source/opt/instrument_pass.cpp
+++ b/source/opt/instrument_pass.cpp
@@ -758,7 +758,6 @@
                                        write_blk_id, merge_blk_id, merge_blk_id,
                                        SpvSelectionControlMaskNone);
     // Close safety test block and gen write block
-    new_blk_ptr->SetParent(&*output_func);
     output_func->AddBasicBlock(std::move(new_blk_ptr));
     new_blk_ptr = MakeUnique<BasicBlock>(std::move(write_label));
     builder.SetInsertPoint(&*new_blk_ptr);
@@ -773,13 +772,11 @@
     }
     // Close write block and gen merge block
     (void)builder.AddBranch(merge_blk_id);
-    new_blk_ptr->SetParent(&*output_func);
     output_func->AddBasicBlock(std::move(new_blk_ptr));
     new_blk_ptr = MakeUnique<BasicBlock>(std::move(merge_label));
     builder.SetInsertPoint(&*new_blk_ptr);
     // Close merge block and function and add function to module
     (void)builder.AddNullaryOp(0, SpvOpReturn);
-    new_blk_ptr->SetParent(&*output_func);
     output_func->AddBasicBlock(std::move(new_blk_ptr));
     std::unique_ptr<Instruction> func_end_inst(
         new Instruction(get_module()->context(), SpvOpFunctionEnd, 0, 0, {}));
@@ -860,7 +857,6 @@
       context(), SpvOpReturnValue, 0, 0,
       std::initializer_list<Operand>{{SPV_OPERAND_TYPE_ID, {last_value_id}}}));
   // Close block and function and add function to module
-  new_blk_ptr->SetParent(&*input_func);
   input_func->AddBasicBlock(std::move(new_blk_ptr));
   std::unique_ptr<Instruction> func_end_inst(
       new Instruction(get_module()->context(), SpvOpFunctionEnd, 0, 0, {}));
diff --git a/source/opt/loop_peeling.cpp b/source/opt/loop_peeling.cpp
index 071c27c..34f0a8d 100644
--- a/source/opt/loop_peeling.cpp
+++ b/source/opt/loop_peeling.cpp
@@ -351,7 +351,6 @@
   std::unique_ptr<BasicBlock> new_bb =
       MakeUnique<BasicBlock>(std::unique_ptr<Instruction>(new Instruction(
           context_, SpvOpLabel, 0, context_->TakeNextId(), {})));
-  new_bb->SetParent(loop_utils_.GetFunction());
   // Update the loop descriptor.
   Loop* in_loop = (*loop_utils_.GetLoopDescriptor())[bb];
   if (in_loop) {
diff --git a/source/opt/merge_return_pass.cpp b/source/opt/merge_return_pass.cpp
index b43eb31..f160104 100644
--- a/source/opt/merge_return_pass.cpp
+++ b/source/opt/merge_return_pass.cpp
@@ -182,7 +182,8 @@
   context()->AnalyzeDefUse(final_return_block_->GetLabelInst());
   context()->set_instr_block(final_return_block_->GetLabelInst(),
                              final_return_block_);
-  final_return_block_->SetParent(function_);
+  assert(final_return_block_->GetParent() == function_ &&
+         "The function should have been set when the block was created.");
 }
 
 void MergeReturnPass::CreateReturn(BasicBlock* block) {
diff --git a/source/opt/wrap_opkill.cpp b/source/opt/wrap_opkill.cpp
index ae1000c..51432a7 100644
--- a/source/opt/wrap_opkill.cpp
+++ b/source/opt/wrap_opkill.cpp
@@ -164,7 +164,6 @@
   bb->AddInstruction(std::move(kill_inst));
 
   // Add the bb to the function
-  bb->SetParent((*killing_func).get());
   (*killing_func)->AddBasicBlock(std::move(bb));
 
   // Add the function to the module.