diff --git a/toolchain/check/convert.cpp b/toolchain/check/convert.cpp
index 2f3575b21b50..c5a43a48febc 100644
--- a/toolchain/check/convert.cpp
+++ b/toolchain/check/convert.cpp
@@ -794,7 +794,7 @@ auto Convert(Context& context, Parse::Node parse_node, SemIR::InstId expr_id,
 
   // We can only perform initialization for complete types.
   if (!context.TryToCompleteType(target.type_id, [&] {
-        CARBON_DIAGNOSTIC(IncompleteTypeInInitialization, Error,
+        CARBON_DIAGNOSTIC(IncompleteTypeInInit, Error,
                           "Initialization of incomplete type `{0}`.",
                           std::string);
         CARBON_DIAGNOSTIC(IncompleteTypeInValueConversion, Error,
@@ -804,7 +804,7 @@ auto Convert(Context& context, Parse::Node parse_node, SemIR::InstId expr_id,
                           "Invalid use of incomplete type `{0}`.", std::string);
         return context.emitter().Build(
             parse_node,
-            target.is_initializer() ? IncompleteTypeInInitialization
+            target.is_initializer() ? IncompleteTypeInInit
             : target.kind == ConversionTarget::Value
                 ? IncompleteTypeInValueConversion
                 : IncompleteTypeInConversion,
diff --git a/toolchain/check/testdata/expression_category/in_place_tuple_initialization.carbon b/toolchain/check/testdata/expression_category/in_place_tuple_init.carbon
similarity index 97%
rename from toolchain/check/testdata/expression_category/in_place_tuple_initialization.carbon
rename to toolchain/check/testdata/expression_category/in_place_tuple_init.carbon
index 55d30e1784c8..0d10f066fbab 100644
--- a/toolchain/check/testdata/expression_category/in_place_tuple_initialization.carbon
+++ b/toolchain/check/testdata/expression_category/in_place_tuple_init.carbon
@@ -22,7 +22,7 @@ fn H() -> i32 {
 // CHECK:STDOUT:   %.loc7_20.3: type = ptr_type (i32, i32)
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: file "in_place_tuple_initialization.carbon" {
+// CHECK:STDOUT: file "in_place_tuple_init.carbon" {
 // CHECK:STDOUT:   %F: <function> = fn_decl @F
 // CHECK:STDOUT:   %G: <function> = fn_decl @G
 // CHECK:STDOUT:   %H: <function> = fn_decl @H
diff --git a/toolchain/diagnostics/diagnostic_kind.def b/toolchain/diagnostics/diagnostic_kind.def
index 84d913055fec..8feba807e7a6 100644
--- a/toolchain/diagnostics/diagnostic_kind.def
+++ b/toolchain/diagnostics/diagnostic_kind.def
@@ -164,7 +164,7 @@ CARBON_DIAGNOSTIC_KIND(RepeatedConst)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInConversion)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInFunctionParam)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInFunctionReturnType)
-CARBON_DIAGNOSTIC_KIND(IncompleteTypeInInitialization)
+CARBON_DIAGNOSTIC_KIND(IncompleteTypeInInit)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInLetDecl)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInMemberAccess)
 CARBON_DIAGNOSTIC_KIND(IncompleteTypeInValueConversion)
diff --git a/toolchain/lower/function_context.cpp b/toolchain/lower/function_context.cpp
index 6cd753c4ac09..891e224c8f4a 100644
--- a/toolchain/lower/function_context.cpp
+++ b/toolchain/lower/function_context.cpp
@@ -78,9 +78,8 @@ auto FunctionContext::CreateSyntheticBlock() -> llvm::BasicBlock* {
   return synthetic_block_;
 }
 
-auto FunctionContext::FinishInitialization(SemIR::TypeId type_id,
-                                           SemIR::InstId dest_id,
-                                           SemIR::InstId source_id) -> void {
+auto FunctionContext::FinishInit(SemIR::TypeId type_id, SemIR::InstId dest_id,
+                                 SemIR::InstId source_id) -> void {
   switch (SemIR::GetInitializingRepresentation(sem_ir(), type_id).kind) {
     case SemIR::InitializingRepresentation::None:
     case SemIR::InitializingRepresentation::InPlace:
diff --git a/toolchain/lower/function_context.h b/toolchain/lower/function_context.h
index 2ca29b7754e7..7c3b96f6ca8a 100644
--- a/toolchain/lower/function_context.h
+++ b/toolchain/lower/function_context.h
@@ -90,8 +90,8 @@ class FunctionContext {
   // initialization of `dest_id` from that initializer. This is a no-op if the
   // initialization was performed in-place, and otherwise performs a store or a
   // copy.
-  auto FinishInitialization(SemIR::TypeId type_id, SemIR::InstId dest_id,
-                            SemIR::InstId init_id) -> void;
+  auto FinishInit(SemIR::TypeId type_id, SemIR::InstId dest_id,
+                  SemIR::InstId init_id) -> void;
 
   auto llvm_context() -> llvm::LLVMContext& {
     return file_context_->llvm_context();
diff --git a/toolchain/lower/handle.cpp b/toolchain/lower/handle.cpp
index 964529b6bde6..976a9faa33c4 100644
--- a/toolchain/lower/handle.cpp
+++ b/toolchain/lower/handle.cpp
@@ -49,7 +49,7 @@ auto HandleArrayInit(FunctionContext& context, SemIR::InstId inst_id,
 auto HandleAssign(FunctionContext& context, SemIR::InstId /*inst_id*/,
                   SemIR::Assign inst) -> void {
   auto storage_type_id = context.sem_ir().insts().Get(inst.lhs_id).type_id();
-  context.FinishInitialization(storage_type_id, inst.lhs_id, inst.rhs_id);
+  context.FinishInit(storage_type_id, inst.lhs_id, inst.rhs_id);
 }
 
 auto HandleBinaryOperatorAdd(FunctionContext& /*context*/,
@@ -190,7 +190,7 @@ auto HandleFunctionDecl(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/,
 auto HandleInitializeFrom(FunctionContext& context, SemIR::InstId /*inst_id*/,
                           SemIR::InitializeFrom inst) -> void {
   auto storage_type_id = context.sem_ir().insts().Get(inst.dest_id).type_id();
-  context.FinishInitialization(storage_type_id, inst.dest_id, inst.src_id);
+  context.FinishInit(storage_type_id, inst.dest_id, inst.src_id);
 }
 
 auto HandleIntegerLiteral(FunctionContext& context, SemIR::InstId inst_id,
diff --git a/toolchain/lower/handle_expr_category.cpp b/toolchain/lower/handle_expr_category.cpp
index 8c860d22859e..776968023e3c 100644
--- a/toolchain/lower/handle_expr_category.cpp
+++ b/toolchain/lower/handle_expr_category.cpp
@@ -37,7 +37,7 @@ auto HandleBindValue(FunctionContext& context, SemIR::InstId inst_id,
 
 auto HandleTemporary(FunctionContext& context, SemIR::InstId inst_id,
                      SemIR::Temporary inst) -> void {
-  context.FinishInitialization(inst.type_id, inst.storage_id, inst.init_id);
+  context.FinishInit(inst.type_id, inst.storage_id, inst.init_id);
   context.SetLocal(inst_id, context.GetValue(inst.storage_id));
 }