diff --git a/toolchain/check/check.cpp b/toolchain/check/check.cpp
index 4460a057b54d..df506b8c4f0c 100644
--- a/toolchain/check/check.cpp
+++ b/toolchain/check/check.cpp
@@ -26,13 +26,13 @@ namespace Carbon::Check {
   auto Handle##Name(Context& context, Parse::Name##Id node_id) -> bool;
 #include "toolchain/parse/node_kind.def"
 
-// Handles the transformation of a SemIRLocation to a DiagnosticLocation.
+// Handles the transformation of a SemIRLoc to a DiagnosticLoc.
 //
 // TODO: Move this to diagnostic_helpers.cpp.
-class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
+class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLoc> {
  public:
   explicit SemIRDiagnosticConverter(
-      const llvm::DenseMap<const SemIR::File*, Parse::NodeLocationConverter*>*
+      const llvm::DenseMap<const SemIR::File*, Parse::NodeLocConverter*>*
           node_converters,
       const SemIR::File* sem_ir)
       : node_converters_(node_converters), sem_ir_(sem_ir) {}
@@ -40,8 +40,8 @@ class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
   // Converts an instruction's location to a diagnostic location, which will be
   // the underlying line of code. Adds context for any imports used in the
   // current SemIR to get to the underlying code.
-  auto ConvertLocation(SemIRLocation loc, ContextFnT context_fn) const
-      -> DiagnosticLocation override {
+  auto ConvertLoc(SemIRLoc loc, ContextFnT context_fn) const
+      -> DiagnosticLoc override {
     // Cursors for the current IR and instruction in that IR.
     const auto* cursor_ir = sem_ir_;
     auto cursor_inst_id = SemIR::InstId::Invalid;
@@ -51,8 +51,8 @@ class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
     auto follow_import_ref = [&](SemIR::ImportIRId ir_id,
                                  SemIR::InstId inst_id) {
       const auto& import_ir = cursor_ir->import_irs().Get(ir_id);
-      auto context_loc = ConvertLocationInFile(cursor_ir, import_ir.node_id,
-                                               loc.token_only, context_fn);
+      auto context_loc = ConvertLocInFile(cursor_ir, import_ir.node_id,
+                                          loc.token_only, context_fn);
       CARBON_DIAGNOSTIC(InImport, Note, "In import.");
       context_fn(context_loc, InImport);
       cursor_ir = import_ir.sem_ir;
@@ -61,8 +61,7 @@ class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
 
     // If the location is is an import, follows it and returns nullopt.
     // Otherwise, it's a parse node, so return the final location.
-    auto handle_loc =
-        [&](SemIR::LocationId loc_id) -> std::optional<DiagnosticLocation> {
+    auto handle_loc = [&](SemIR::LocId loc_id) -> std::optional<DiagnosticLoc> {
       if (loc_id.is_import_ir_inst_id()) {
         auto import_ir_inst =
             cursor_ir->import_ir_insts().Get(loc_id.import_ir_inst_id());
@@ -70,8 +69,8 @@ class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
         return std::nullopt;
       } else {
         // Parse nodes always refer to the current IR.
-        return ConvertLocationInFile(cursor_ir, loc_id.node_id(),
-                                     loc.token_only, context_fn);
+        return ConvertLocInFile(cursor_ir, loc_id.node_id(), loc.token_only,
+                                context_fn);
       }
     };
 
@@ -87,7 +86,7 @@ class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
 
     while (true) {
       // If the parse node is valid, use it for the location.
-      if (auto loc_id = cursor_ir->insts().GetLocationId(cursor_inst_id);
+      if (auto loc_id = cursor_ir->insts().GetLocId(cursor_inst_id);
           loc_id.is_valid()) {
         if (auto diag_loc = handle_loc(loc_id)) {
           return *diag_loc;
@@ -114,8 +113,8 @@ class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
       }
 
       // Invalid parse node but not an import; just nothing to point at.
-      return ConvertLocationInFile(cursor_ir, Parse::NodeId::Invalid,
-                                   loc.token_only, context_fn);
+      return ConvertLocInFile(cursor_ir, Parse::NodeId::Invalid, loc.token_only,
+                              context_fn);
     }
   }
 
@@ -130,20 +129,20 @@ class SemIRDiagnosticConverter : public DiagnosticConverter<SemIRLocation> {
       return llvm::APSInt(typed_int->value,
                           !sem_ir_->types().IsSignedInt(typed_int->type));
     }
-    return DiagnosticConverter<SemIRLocation>::ConvertArg(arg);
+    return DiagnosticConverter<SemIRLoc>::ConvertArg(arg);
   }
 
  private:
-  auto ConvertLocationInFile(const SemIR::File* sem_ir, Parse::NodeId node_id,
-                             bool token_only, ContextFnT context_fn) const
-      -> DiagnosticLocation {
+  auto ConvertLocInFile(const SemIR::File* sem_ir, Parse::NodeId node_id,
+                        bool token_only, ContextFnT context_fn) const
+      -> DiagnosticLoc {
     auto it = node_converters_->find(sem_ir);
     CARBON_CHECK(it != node_converters_->end());
-    return it->second->ConvertLocation(Parse::NodeLocation(node_id, token_only),
-                                       context_fn);
+    return it->second->ConvertLoc(Parse::NodeLoc(node_id, token_only),
+                                  context_fn);
   }
 
-  const llvm::DenseMap<const SemIR::File*, Parse::NodeLocationConverter*>*
+  const llvm::DenseMap<const SemIR::File*, Parse::NodeLocConverter*>*
       node_converters_;
   const SemIR::File* sem_ir_;
 };
@@ -181,9 +180,9 @@ struct UnitInfo {
   Unit* unit;
 
   // Emitter information.
-  Parse::NodeLocationConverter converter;
+  Parse::NodeLocConverter converter;
   ErrorTrackingDiagnosticConsumer err_tracker;
-  DiagnosticEmitter<Parse::NodeLocation> emitter;
+  DiagnosticEmitter<Parse::NodeLoc> emitter;
 
   // A map of package names to outgoing imports. If the
   // import's target isn't available, the unit will be nullptr to assist with
@@ -300,7 +299,7 @@ static auto ProcessNodeIds(Context& context,
 
 // Produces and checks the IR for the provided Parse::Tree.
 static auto CheckParseTree(
-    llvm::DenseMap<const SemIR::File*, Parse::NodeLocationConverter*>*
+    llvm::DenseMap<const SemIR::File*, Parse::NodeLocConverter*>*
         node_converters,
     const SemIR::File& builtin_ir, UnitInfo& unit_info,
     llvm::raw_ostream* vlog_stream) -> void {
@@ -626,8 +625,7 @@ auto CheckParseTrees(const SemIR::File& builtin_ir,
     }
   }
 
-  llvm::DenseMap<const SemIR::File*, Parse::NodeLocationConverter*>
-      node_converters;
+  llvm::DenseMap<const SemIR::File*, Parse::NodeLocConverter*> node_converters;
 
   // Check everything with no dependencies. Earlier entries with dependencies
   // will be checked as soon as all their dependencies have been checked.
diff --git a/toolchain/check/context.cpp b/toolchain/check/context.cpp
index 054d66ee5868..1e426644d0aa 100644
--- a/toolchain/check/context.cpp
+++ b/toolchain/check/context.cpp
@@ -51,7 +51,7 @@ Context::Context(const Lex::TokenizedBuffer& tokens, DiagnosticEmitter& emitter,
        SemIR::TypeId::TypeType});
 }
 
-auto Context::TODO(SemIRLocation loc, std::string label) -> bool {
+auto Context::TODO(SemIRLoc loc, std::string label) -> bool {
   CARBON_DIAGNOSTIC(SemanticsTodo, Error, "Semantics TODO: `{0}`.",
                     std::string);
   emitter_->Emit(loc, SemanticsTodo, std::move(label));
@@ -68,7 +68,7 @@ auto Context::VerifyOnFinish() -> void {
   param_and_arg_refs_stack_.VerifyOnFinish();
 }
 
-auto Context::AddInstInNoBlock(SemIR::LocationIdAndInst loc_id_and_inst)
+auto Context::AddInstInNoBlock(SemIR::LocIdAndInst loc_id_and_inst)
     -> SemIR::InstId {
   auto inst_id = sem_ir().insts().AddInNoBlock(loc_id_and_inst);
   CARBON_VLOG() << "AddInst: " << loc_id_and_inst.inst << "\n";
@@ -83,22 +83,21 @@ auto Context::AddInstInNoBlock(SemIR::LocationIdAndInst loc_id_and_inst)
   return inst_id;
 }
 
-auto Context::AddInst(SemIR::LocationIdAndInst loc_id_and_inst)
-    -> SemIR::InstId {
+auto Context::AddInst(SemIR::LocIdAndInst loc_id_and_inst) -> SemIR::InstId {
   auto inst_id = AddInstInNoBlock(loc_id_and_inst);
   inst_block_stack_.AddInstId(inst_id);
   return inst_id;
 }
 
-auto Context::AddPlaceholderInstInNoBlock(
-    SemIR::LocationIdAndInst loc_id_and_inst) -> SemIR::InstId {
+auto Context::AddPlaceholderInstInNoBlock(SemIR::LocIdAndInst loc_id_and_inst)
+    -> SemIR::InstId {
   auto inst_id = sem_ir().insts().AddInNoBlock(loc_id_and_inst);
   CARBON_VLOG() << "AddPlaceholderInst: " << loc_id_and_inst.inst << "\n";
   constant_values().Set(inst_id, SemIR::ConstantId::Invalid);
   return inst_id;
 }
 
-auto Context::AddPlaceholderInst(SemIR::LocationIdAndInst loc_id_and_inst)
+auto Context::AddPlaceholderInst(SemIR::LocIdAndInst loc_id_and_inst)
     -> SemIR::InstId {
   auto inst_id = AddPlaceholderInstInNoBlock(loc_id_and_inst);
   inst_block_stack_.AddInstId(inst_id);
@@ -112,14 +111,14 @@ auto Context::AddConstant(SemIR::Inst inst, bool is_symbolic)
   return const_id;
 }
 
-auto Context::AddInstAndPush(SemIR::LocationIdAndInst loc_id_and_inst) -> void {
+auto Context::AddInstAndPush(SemIR::LocIdAndInst loc_id_and_inst) -> void {
   auto inst_id = AddInst(loc_id_and_inst);
   node_stack_.Push(loc_id_and_inst.loc_id.node_id(), inst_id);
 }
 
-auto Context::ReplaceLocationIdAndInstBeforeConstantUse(
-    SemIR::InstId inst_id, SemIR::LocationIdAndInst loc_id_and_inst) -> void {
-  sem_ir().insts().SetLocationIdAndInst(inst_id, loc_id_and_inst);
+auto Context::ReplaceLocIdAndInstBeforeConstantUse(
+    SemIR::InstId inst_id, SemIR::LocIdAndInst loc_id_and_inst) -> void {
+  sem_ir().insts().SetLocIdAndInst(inst_id, loc_id_and_inst);
 
   CARBON_VLOG() << "ReplaceInst: " << inst_id << " -> " << loc_id_and_inst.inst
                 << "\n";
@@ -169,8 +168,8 @@ auto Context::AddImportRef(SemIR::ImportIRId ir_id, SemIR::InstId inst_id)
   return import_ref_id;
 }
 
-auto Context::DiagnoseDuplicateName(SemIRLocation dup_def,
-                                    SemIRLocation prev_def) -> void {
+auto Context::DiagnoseDuplicateName(SemIRLoc dup_def, SemIRLoc prev_def)
+    -> void {
   CARBON_DIAGNOSTIC(NameDeclDuplicate, Error,
                     "Duplicate name being declared in the same scope.");
   CARBON_DIAGNOSTIC(NameDeclPrevious, Note,
@@ -180,8 +179,8 @@ auto Context::DiagnoseDuplicateName(SemIRLocation dup_def,
       .Emit();
 }
 
-auto Context::DiagnoseNameNotFound(SemIR::LocationId loc_id,
-                                   SemIR::NameId name_id) -> void {
+auto Context::DiagnoseNameNotFound(SemIR::LocId loc_id, SemIR::NameId name_id)
+    -> void {
   CARBON_DIAGNOSTIC(NameNotFound, Error, "Name `{0}` not found.",
                     SemIR::NameId);
   emitter_->Emit(loc_id, NameNotFound, name_id);
@@ -226,7 +225,7 @@ auto Context::AddNameToLookup(SemIR::NameId name_id, SemIR::InstId target_id)
   }
 }
 
-auto Context::LookupNameInDecl(SemIR::LocationId loc_id, SemIR::NameId name_id,
+auto Context::LookupNameInDecl(SemIR::LocId loc_id, SemIR::NameId name_id,
                                SemIR::NameScopeId scope_id) -> SemIR::InstId {
   if (!scope_id.is_valid()) {
     // Look for a name in the current scope only. There are two cases where the
@@ -296,7 +295,7 @@ auto Context::LookupUnqualifiedName(Parse::NodeId node_id,
 }
 
 // Handles lookup through the import_ir_scopes for LookupNameInExactScope.
-static auto LookupInImportIRScopes(Context& context, SemIRLocation loc,
+static auto LookupInImportIRScopes(Context& context, SemIRLoc loc,
                                    SemIR::NameId name_id,
                                    const SemIR::NameScope& scope)
     -> SemIR::InstId {
@@ -350,7 +349,7 @@ static auto LookupInImportIRScopes(Context& context, SemIRLocation loc,
   return result_id;
 }
 
-auto Context::LookupNameInExactScope(SemIRLocation loc, SemIR::NameId name_id,
+auto Context::LookupNameInExactScope(SemIRLoc loc, SemIR::NameId name_id,
                                      const SemIR::NameScope& scope)
     -> SemIR::InstId {
   if (auto it = scope.names.find(name_id); it != scope.names.end()) {
diff --git a/toolchain/check/context.h b/toolchain/check/context.h
index 11fbc2b76976..62f5d4baddcd 100644
--- a/toolchain/check/context.h
+++ b/toolchain/check/context.h
@@ -26,7 +26,7 @@ namespace Carbon::Check {
 // Context and shared functionality for semantics handlers.
 class Context {
  public:
-  using DiagnosticEmitter = Carbon::DiagnosticEmitter<SemIRLocation>;
+  using DiagnosticEmitter = Carbon::DiagnosticEmitter<SemIRLoc>;
   using DiagnosticBuilder = DiagnosticEmitter::DiagnosticBuilder;
 
   // Stores references for work.
@@ -35,44 +35,43 @@ class Context {
                    SemIR::File& sem_ir, llvm::raw_ostream* vlog_stream);
 
   // Marks an implementation TODO. Always returns false.
-  auto TODO(SemIRLocation loc, std::string label) -> bool;
+  auto TODO(SemIRLoc loc, std::string label) -> bool;
 
   // Runs verification that the processing cleanly finished.
   auto VerifyOnFinish() -> void;
 
   // Adds an instruction to the current block, returning the produced ID.
-  auto AddInst(SemIR::LocationIdAndInst loc_id_and_inst) -> SemIR::InstId;
+  auto AddInst(SemIR::LocIdAndInst loc_id_and_inst) -> SemIR::InstId;
 
   // Adds an instruction in no block, returning the produced ID. Should be used
   // rarely.
-  auto AddInstInNoBlock(SemIR::LocationIdAndInst loc_id_and_inst)
-      -> SemIR::InstId;
+  auto AddInstInNoBlock(SemIR::LocIdAndInst loc_id_and_inst) -> SemIR::InstId;
 
   // Adds an instruction to the current block, returning the produced ID. The
   // instruction is a placeholder that is expected to be replaced by
   // `ReplaceInstBeforeConstantUse`.
-  auto AddPlaceholderInst(SemIR::LocationIdAndInst loc_id_and_inst)
-      -> SemIR::InstId;
+  auto AddPlaceholderInst(SemIR::LocIdAndInst loc_id_and_inst) -> SemIR::InstId;
 
   // Adds an instruction in no block, returning the produced ID. Should be used
   // rarely. The instruction is a placeholder that is expected to be replaced by
   // `ReplaceInstBeforeConstantUse`.
-  auto AddPlaceholderInstInNoBlock(SemIR::LocationIdAndInst loc_id_and_inst)
+  auto AddPlaceholderInstInNoBlock(SemIR::LocIdAndInst loc_id_and_inst)
       -> SemIR::InstId;
 
   // Adds an instruction to the constants block, returning the produced ID.
   auto AddConstant(SemIR::Inst inst, bool is_symbolic) -> SemIR::ConstantId;
 
   // Pushes a parse tree node onto the stack, storing the SemIR::Inst as the
-  // result. Only valid if the LocationId is for a NodeId.
-  auto AddInstAndPush(SemIR::LocationIdAndInst loc_id_and_inst) -> void;
+  // result. Only valid if the LocId is for a NodeId.
+  auto AddInstAndPush(SemIR::LocIdAndInst loc_id_and_inst) -> void;
 
   // Replaces the instruction `inst_id` with `loc_id_and_inst`. The instruction
   // is required to not have been used in any constant evaluation, either
   // because it's newly created and entirely unused, or because it's only used
   // in a position that constant evaluation ignores, such as a return slot.
-  auto ReplaceLocationIdAndInstBeforeConstantUse(
-      SemIR::InstId inst_id, SemIR::LocationIdAndInst loc_id_and_inst) -> void;
+  auto ReplaceLocIdAndInstBeforeConstantUse(SemIR::InstId inst_id,
+                                            SemIR::LocIdAndInst loc_id_and_inst)
+      -> void;
 
   // Replaces the instruction `inst_id` with `inst`, not affecting location.
   // The instruction is required to not have been used in any constant
@@ -94,7 +93,7 @@ class Context {
   // remain const.
   auto SetNamespaceNodeId(SemIR::InstId inst_id, Parse::NodeId node_id)
       -> void {
-    sem_ir().insts().SetLocationId(inst_id, SemIR::LocationId(node_id));
+    sem_ir().insts().SetLocId(inst_id, SemIR::LocId(node_id));
   }
 
   // Adds a name to name lookup. Prints a diagnostic for name conflicts.
@@ -103,7 +102,7 @@ class Context {
   // Performs name lookup in a specified scope for a name appearing in a
   // declaration, returning the referenced instruction. If scope_id is invalid,
   // uses the current contextual scope.
-  auto LookupNameInDecl(SemIR::LocationId loc_id, SemIR::NameId name_id,
+  auto LookupNameInDecl(SemIR::LocId loc_id, SemIR::NameId name_id,
                         SemIR::NameScopeId scope_id) -> SemIR::InstId;
 
   // Performs an unqualified name lookup, returning the referenced instruction.
@@ -113,7 +112,7 @@ class Context {
   // Performs a name lookup in a specified scope, returning the referenced
   // instruction. Does not look into extended scopes. Returns an invalid
   // instruction if the name is not found.
-  auto LookupNameInExactScope(SemIRLocation loc, SemIR::NameId name_id,
+  auto LookupNameInExactScope(SemIRLoc loc, SemIR::NameId name_id,
                               const SemIR::NameScope& scope) -> SemIR::InstId;
 
   // Performs a qualified name lookup in a specified scope and in scopes that
@@ -123,12 +122,10 @@ class Context {
       -> SemIR::InstId;
 
   // Prints a diagnostic for a duplicate name.
-  auto DiagnoseDuplicateName(SemIRLocation dup_def, SemIRLocation prev_def)
-      -> void;
+  auto DiagnoseDuplicateName(SemIRLoc dup_def, SemIRLoc prev_def) -> void;
 
   // Prints a diagnostic for a missing name.
-  auto DiagnoseNameNotFound(SemIR::LocationId loc_id, SemIR::NameId name_id)
-      -> void;
+  auto DiagnoseNameNotFound(SemIR::LocId loc_id, SemIR::NameId name_id) -> void;
 
   // Adds a note to a diagnostic explaining that a class is incomplete.
   auto NoteIncompleteClass(SemIR::ClassId class_id, DiagnosticBuilder& builder)
diff --git a/toolchain/check/convert.cpp b/toolchain/check/convert.cpp
index aafd9a6c25b4..581af82d51c0 100644
--- a/toolchain/check/convert.cpp
+++ b/toolchain/check/convert.cpp
@@ -96,7 +96,7 @@ static auto FinalizeTemporary(Context& context, SemIR::InstId init_id,
         << sem_ir.insts().Get(return_slot_id);
     auto init = sem_ir.insts().Get(init_id);
     return context.AddInst(
-        {sem_ir.insts().GetLocationId(init_id),
+        {sem_ir.insts().GetLocId(init_id),
          SemIR::Temporary{init.type_id(), return_slot_id, init_id}});
   }
 
@@ -111,7 +111,7 @@ static auto FinalizeTemporary(Context& context, SemIR::InstId init_id,
   // materialize and initialize a temporary, rather than two separate
   // instructions.
   auto init = sem_ir.insts().Get(init_id);
-  auto loc_id = sem_ir.insts().GetLocationId(init_id);
+  auto loc_id = sem_ir.insts().GetLocId(init_id);
   auto temporary_id =
       context.AddInst({loc_id, SemIR::TemporaryStorage{init.type_id()}});
   return context.AddInst(
@@ -131,7 +131,7 @@ static auto MaterializeIfInitializing(Context& context, SemIR::InstId expr_id)
 
 // Creates and adds an instruction to perform element access into an aggregate.
 template <typename AccessInstT, typename InstBlockT>
-static auto MakeElementAccessInst(Context& context, SemIR::LocationId loc_id,
+static auto MakeElementAccessInst(Context& context, SemIR::LocId loc_id,
                                   SemIR::InstId aggregate_id,
                                   SemIR::TypeId elem_type_id, InstBlockT& block,
                                   std::size_t i) {
@@ -166,7 +166,7 @@ static auto MakeElementAccessInst(Context& context, SemIR::LocationId loc_id,
 // instruction used to access the destination element.
 template <typename SourceAccessInstT, typename TargetAccessInstT>
 static auto ConvertAggregateElement(
-    Context& context, SemIR::LocationId loc_id, SemIR::InstId src_id,
+    Context& context, SemIR::LocId loc_id, SemIR::InstId src_id,
     SemIR::TypeId src_elem_type,
     llvm::ArrayRef<SemIR::InstId> src_literal_elems,
     ConversionTarget::Kind kind, SemIR::InstId target_id,
@@ -206,7 +206,7 @@ static auto ConvertTupleToArray(Context& context, SemIR::TupleType tuple_type,
   auto tuple_elem_types = sem_ir.type_blocks().Get(tuple_type.elements_id);
 
   auto value = sem_ir.insts().Get(value_id);
-  auto value_loc_id = sem_ir.insts().GetLocationId(value_id);
+  auto value_loc_id = sem_ir.insts().GetLocId(value_id);
 
   // If we're initializing from a tuple literal, we will use its elements
   // directly. Otherwise, materialize a temporary if needed and index into the
@@ -290,7 +290,7 @@ static auto ConvertTupleToTuple(Context& context, SemIR::TupleType src_type,
   auto dest_elem_types = sem_ir.type_blocks().Get(dest_type.elements_id);
 
   auto value = sem_ir.insts().Get(value_id);
-  auto value_loc_id = sem_ir.insts().GetLocationId(value_id);
+  auto value_loc_id = sem_ir.insts().GetLocId(value_id);
 
   // If we're initializing from a tuple literal, we will use its elements
   // directly. Otherwise, materialize a temporary if needed and index into the
@@ -374,7 +374,7 @@ static auto ConvertStructToStructOrClass(Context& context,
   auto dest_elem_fields = sem_ir.inst_blocks().Get(dest_type.fields_id);
 
   auto value = sem_ir.insts().Get(value_id);
-  auto value_loc_id = sem_ir.insts().GetLocationId(value_id);
+  auto value_loc_id = sem_ir.insts().GetLocId(value_id);
 
   // If we're initializing from a struct literal, we will use its elements
   // directly. Otherwise, materialize a temporary if needed and index into the
@@ -539,7 +539,7 @@ static auto ConvertStructToClass(Context& context, SemIR::StructType src_type,
     target.kind = ConversionTarget::Initializer;
     target.init_block = &target_block;
     target.init_id =
-        target_block.AddInst({context.insts().GetLocationId(value_id),
+        target_block.AddInst({context.insts().GetLocId(value_id),
                               SemIR::TemporaryStorage{target.type_id}});
   }
 
@@ -549,7 +549,7 @@ static auto ConvertStructToClass(Context& context, SemIR::StructType src_type,
   if (need_temporary) {
     target_block.InsertHere();
     result_id = context.AddInst(
-        {context.insts().GetLocationId(value_id),
+        {context.insts().GetLocId(value_id),
          SemIR::Temporary{target.type_id, target.init_id, result_id}});
   }
   return result_id;
@@ -596,7 +596,7 @@ static auto ComputeInheritancePath(Context& context, SemIR::TypeId derived_id,
 
 // Performs a conversion from a derived class value or reference to a base class
 // value or reference.
-static auto ConvertDerivedToBase(Context& context, SemIR::LocationId loc_id,
+static auto ConvertDerivedToBase(Context& context, SemIR::LocId loc_id,
                                  SemIR::InstId value_id,
                                  const InheritancePath& path) -> SemIR::InstId {
   // Materialize a temporary if necessary.
@@ -614,7 +614,7 @@ static auto ConvertDerivedToBase(Context& context, SemIR::LocationId loc_id,
 
 // Performs a conversion from a derived class pointer to a base class pointer.
 static auto ConvertDerivedPointerToBasePointer(
-    Context& context, SemIR::LocationId loc_id, SemIR::PointerType src_ptr_type,
+    Context& context, SemIR::LocId loc_id, SemIR::PointerType src_ptr_type,
     SemIR::TypeId dest_ptr_type_id, SemIR::InstId ptr_id,
     const InheritancePath& path) -> SemIR::InstId {
   // Form `*p`.
@@ -651,7 +651,7 @@ static auto IsValidExprCategoryForConversionTarget(
   }
 }
 
-static auto PerformBuiltinConversion(Context& context, SemIR::LocationId loc_id,
+static auto PerformBuiltinConversion(Context& context, SemIR::LocId loc_id,
                                      SemIR::InstId value_id,
                                      ConversionTarget target) -> SemIR::InstId {
   auto& sem_ir = context.sem_ir();
@@ -849,7 +849,7 @@ static auto PerformCopy(Context& context, SemIR::InstId expr_id)
   return SemIR::InstId::BuiltinError;
 }
 
-auto Convert(Context& context, SemIR::LocationId loc_id, SemIR::InstId expr_id,
+auto Convert(Context& context, SemIR::LocId loc_id, SemIR::InstId expr_id,
              ConversionTarget target) -> SemIR::InstId {
   auto& sem_ir = context.sem_ir();
   auto orig_expr_id = expr_id;
@@ -923,7 +923,7 @@ auto Convert(Context& context, SemIR::LocationId loc_id, SemIR::InstId expr_id,
   // Track that we performed a type conversion, if we did so.
   if (orig_expr_id != expr_id) {
     expr_id = context.AddInst(
-        {context.insts().GetLocationId(orig_expr_id),
+        {context.insts().GetLocId(orig_expr_id),
          SemIR::Converted{target.type_id, orig_expr_id, expr_id}});
   }
 
@@ -974,7 +974,7 @@ auto Convert(Context& context, SemIR::LocationId loc_id, SemIR::InstId expr_id,
 
       // If we have a reference and don't want one, form a value binding.
       // TODO: Support types with custom value representations.
-      expr_id = context.AddInst({context.insts().GetLocationId(expr_id),
+      expr_id = context.AddInst({context.insts().GetLocId(expr_id),
                                  SemIR::BindValue{expr.type_id(), expr_id}});
       // We now have a value expression.
       [[fallthrough]];
@@ -1001,9 +1001,8 @@ auto Convert(Context& context, SemIR::LocationId loc_id, SemIR::InstId expr_id,
   return expr_id;
 }
 
-auto Initialize(Context& context, SemIR::LocationId loc_id,
-                SemIR::InstId target_id, SemIR::InstId value_id)
-    -> SemIR::InstId {
+auto Initialize(Context& context, SemIR::LocId loc_id, SemIR::InstId target_id,
+                SemIR::InstId value_id) -> SemIR::InstId {
   PendingBlock target_block(context);
   return Convert(context, loc_id, value_id,
                  {.kind = ConversionTarget::Initializer,
@@ -1014,33 +1013,33 @@ auto Initialize(Context& context, SemIR::LocationId loc_id,
 
 auto ConvertToValueExpr(Context& context, SemIR::InstId expr_id)
     -> SemIR::InstId {
-  return Convert(context, context.insts().GetLocationId(expr_id), expr_id,
+  return Convert(context, context.insts().GetLocId(expr_id), expr_id,
                  {.kind = ConversionTarget::Value,
                   .type_id = context.insts().Get(expr_id).type_id()});
 }
 
 auto ConvertToValueOrRefExpr(Context& context, SemIR::InstId expr_id)
     -> SemIR::InstId {
-  return Convert(context, context.insts().GetLocationId(expr_id), expr_id,
+  return Convert(context, context.insts().GetLocId(expr_id), expr_id,
                  {.kind = ConversionTarget::ValueOrRef,
                   .type_id = context.insts().Get(expr_id).type_id()});
 }
 
-auto ConvertToValueOfType(Context& context, SemIR::LocationId loc_id,
+auto ConvertToValueOfType(Context& context, SemIR::LocId loc_id,
                           SemIR::InstId expr_id, SemIR::TypeId type_id)
     -> SemIR::InstId {
   return Convert(context, loc_id, expr_id,
                  {.kind = ConversionTarget::Value, .type_id = type_id});
 }
 
-auto ConvertToValueOrRefOfType(Context& context, SemIR::LocationId loc_id,
+auto ConvertToValueOrRefOfType(Context& context, SemIR::LocId loc_id,
                                SemIR::InstId expr_id, SemIR::TypeId type_id)
     -> SemIR::InstId {
   return Convert(context, loc_id, expr_id,
                  {.kind = ConversionTarget::ValueOrRef, .type_id = type_id});
 }
 
-auto ConvertToBoolValue(Context& context, SemIR::LocationId loc_id,
+auto ConvertToBoolValue(Context& context, SemIR::LocId loc_id,
                         SemIR::InstId value_id) -> SemIR::InstId {
   return ConvertToValueOfType(
       context, loc_id, value_id,
@@ -1057,7 +1056,7 @@ auto ConvertForExplicitAs(Context& context, Parse::NodeId as_node,
 CARBON_DIAGNOSTIC(InCallToFunction, Note, "Calling function declared here.");
 
 // Convert the object argument in a method call to match the `self` parameter.
-static auto ConvertSelf(Context& context, SemIR::LocationId call_loc_id,
+static auto ConvertSelf(Context& context, SemIR::LocId call_loc_id,
                         SemIR::InstId callee_id,
                         std::optional<SemIR::AddrPattern> addr_pattern,
                         SemIR::InstId self_param_id, SemIR::Param self_param,
@@ -1099,7 +1098,7 @@ static auto ConvertSelf(Context& context, SemIR::LocationId call_loc_id,
         context.emitter().Emit(TokenOnly(call_loc_id), AddrSelfIsNonRef);
         return SemIR::InstId::BuiltinError;
     }
-    auto loc_id = context.insts().GetLocationId(self_or_addr_id);
+    auto loc_id = context.insts().GetLocId(self_or_addr_id);
     self_or_addr_id = context.AddInst(
         {loc_id, SemIR::AddrOf{context.GetPointerType(self.type_id()),
                                self_or_addr_id}});
@@ -1109,7 +1108,7 @@ static auto ConvertSelf(Context& context, SemIR::LocationId call_loc_id,
                               self_param.type_id);
 }
 
-auto ConvertCallArgs(Context& context, SemIR::LocationId call_loc_id,
+auto ConvertCallArgs(Context& context, SemIR::LocId call_loc_id,
                      SemIR::InstId self_id,
                      llvm::ArrayRef<SemIR::InstId> arg_refs,
                      SemIR::InstId return_storage_id, SemIR::InstId callee_id,
@@ -1191,8 +1190,8 @@ auto ConvertCallArgs(Context& context, SemIR::LocationId call_loc_id,
   return context.inst_blocks().Add(args);
 }
 
-auto ExprAsType(Context& context, SemIR::LocationId loc_id,
-                SemIR::InstId value_id) -> SemIR::TypeId {
+auto ExprAsType(Context& context, SemIR::LocId loc_id, SemIR::InstId value_id)
+    -> SemIR::TypeId {
   auto type_inst_id =
       ConvertToValueOfType(context, loc_id, value_id, SemIR::TypeId::TypeType);
   if (type_inst_id == SemIR::InstId::BuiltinError) {
diff --git a/toolchain/check/convert.h b/toolchain/check/convert.h
index 34f2f99377ce..ac7cbf295dd4 100644
--- a/toolchain/check/convert.h
+++ b/toolchain/check/convert.h
@@ -50,15 +50,14 @@ struct ConversionTarget {
 };
 
 // Convert a value to another type and expression category.
-auto Convert(Context& context, SemIR::LocationId loc_id, SemIR::InstId expr_id,
+auto Convert(Context& context, SemIR::LocId loc_id, SemIR::InstId expr_id,
              ConversionTarget target) -> SemIR::InstId;
 
 // Performs initialization of `target_id` from `value_id`. Returns the
 // possibly-converted initializing expression, which should be assigned to the
 // target using a suitable node for the kind of initialization.
-auto Initialize(Context& context, SemIR::LocationId loc_id,
-                SemIR::InstId target_id, SemIR::InstId value_id)
-    -> SemIR::InstId;
+auto Initialize(Context& context, SemIR::LocId loc_id, SemIR::InstId target_id,
+                SemIR::InstId value_id) -> SemIR::InstId;
 
 // Convert the given expression to a value expression of the same type.
 auto ConvertToValueExpr(Context& context, SemIR::InstId expr_id)
@@ -70,18 +69,18 @@ auto ConvertToValueOrRefExpr(Context& context, SemIR::InstId expr_id)
     -> SemIR::InstId;
 
 // Converts `expr_id` to a value expression of type `type_id`.
-auto ConvertToValueOfType(Context& context, SemIR::LocationId loc_id,
+auto ConvertToValueOfType(Context& context, SemIR::LocId loc_id,
                           SemIR::InstId expr_id, SemIR::TypeId type_id)
     -> SemIR::InstId;
 
 // Convert the given expression to a value or reference expression of the given
 // type.
-auto ConvertToValueOrRefOfType(Context& context, SemIR::LocationId loc_id,
+auto ConvertToValueOrRefOfType(Context& context, SemIR::LocId loc_id,
                                SemIR::InstId expr_id, SemIR::TypeId type_id)
     -> SemIR::InstId;
 
 // Converts `value_id` to a value expression of type `bool`.
-auto ConvertToBoolValue(Context& context, SemIR::LocationId loc_id,
+auto ConvertToBoolValue(Context& context, SemIR::LocId loc_id,
                         SemIR::InstId value_id) -> SemIR::InstId;
 
 // Converts `value_id` to type `type_id` for an `as` expression.
@@ -92,7 +91,7 @@ auto ConvertForExplicitAs(Context& context, Parse::NodeId as_node,
 // Implicitly converts a set of arguments to match the parameter types in a
 // function call. Returns a block containing the converted implicit and explicit
 // argument values.
-auto ConvertCallArgs(Context& context, SemIR::LocationId call_loc_id,
+auto ConvertCallArgs(Context& context, SemIR::LocId call_loc_id,
                      SemIR::InstId self_id,
                      llvm::ArrayRef<SemIR::InstId> arg_refs,
                      SemIR::InstId return_storage_id, SemIR::InstId callee_id,
@@ -100,8 +99,8 @@ auto ConvertCallArgs(Context& context, SemIR::LocationId call_loc_id,
                      SemIR::InstBlockId param_refs_id) -> SemIR::InstBlockId;
 
 // Converts an expression for use as a type.
-auto ExprAsType(Context& context, SemIR::LocationId loc_id,
-                SemIR::InstId value_id) -> SemIR::TypeId;
+auto ExprAsType(Context& context, SemIR::LocId loc_id, SemIR::InstId value_id)
+    -> SemIR::TypeId;
 
 }  // namespace Carbon::Check
 
diff --git a/toolchain/check/decl_name_stack.cpp b/toolchain/check/decl_name_stack.cpp
index 7a288722a474..5106648fca24 100644
--- a/toolchain/check/decl_name_stack.cpp
+++ b/toolchain/check/decl_name_stack.cpp
@@ -15,7 +15,7 @@ auto DeclNameStack::MakeEmptyNameContext() -> NameContext {
       .target_scope_id = context_->scope_stack().PeekNameScopeId()};
 }
 
-auto DeclNameStack::MakeUnqualifiedName(SemIR::LocationId loc_id,
+auto DeclNameStack::MakeUnqualifiedName(SemIR::LocId loc_id,
                                         SemIR::NameId name_id) -> NameContext {
   NameContext context = MakeEmptyNameContext();
   ApplyNameQualifierTo(context, loc_id, name_id, /*is_unqualified=*/true);
@@ -125,14 +125,14 @@ auto DeclNameStack::AddNameToLookup(NameContext name_context,
   }
 }
 
-auto DeclNameStack::ApplyNameQualifier(SemIR::LocationId loc_id,
+auto DeclNameStack::ApplyNameQualifier(SemIR::LocId loc_id,
                                        SemIR::NameId name_id) -> void {
   ApplyNameQualifierTo(decl_name_stack_.back(), loc_id, name_id,
                        /*is_unqualified=*/false);
 }
 
 auto DeclNameStack::ApplyNameQualifierTo(NameContext& name_context,
-                                         SemIR::LocationId loc_id,
+                                         SemIR::LocId loc_id,
                                          SemIR::NameId name_id,
                                          bool is_unqualified) -> void {
   if (TryResolveQualifier(name_context, loc_id)) {
@@ -241,7 +241,7 @@ auto DeclNameStack::UpdateScopeIfNeeded(NameContext& name_context,
 }
 
 auto DeclNameStack::TryResolveQualifier(NameContext& name_context,
-                                        SemIR::LocationId loc_id) -> bool {
+                                        SemIR::LocId loc_id) -> bool {
   // Update has_qualifiers based on the state before any possible changes. If
   // this is the first qualifier, it may just be the name.
   name_context.has_qualifiers = name_context.state != NameContext::State::Empty;
diff --git a/toolchain/check/decl_name_stack.h b/toolchain/check/decl_name_stack.h
index 2341547f9b0a..5f0100013243 100644
--- a/toolchain/check/decl_name_stack.h
+++ b/toolchain/check/decl_name_stack.h
@@ -124,7 +124,7 @@ class DeclNameStack {
     SemIR::NameScopeId target_scope_id;
 
     // The last location ID used.
-    SemIR::LocationId loc_id = SemIR::LocationId::Invalid;
+    SemIR::LocId loc_id = SemIR::LocId::Invalid;
 
     union {
       // The ID of a resolved qualifier, including both identifiers and
@@ -176,14 +176,13 @@ class DeclNameStack {
   // unqualified name in the current context. This is suitable for adding to
   // name lookup in situations where a qualified name is not permitted, such as
   // a pattern binding.
-  auto MakeUnqualifiedName(SemIR::LocationId loc_id, SemIR::NameId name_id)
+  auto MakeUnqualifiedName(SemIR::LocId loc_id, SemIR::NameId name_id)
       -> NameContext;
 
   // Applies a Name from the name stack to the top of the declaration name
   // stack. This will enter the scope corresponding to the name if the name
   // describes an existing scope, such as a namespace or a defined class.
-  auto ApplyNameQualifier(SemIR::LocationId loc_id, SemIR::NameId name_id)
-      -> void;
+  auto ApplyNameQualifier(SemIR::LocId loc_id, SemIR::NameId name_id) -> void;
 
   // Adds a name to name lookup. Prints a diagnostic for name conflicts.
   auto AddNameToLookup(NameContext name_context, SemIR::InstId target_id)
@@ -199,12 +198,12 @@ class DeclNameStack {
   auto MakeEmptyNameContext() -> NameContext;
 
   // Applies a Name from the name stack to given name context.
-  auto ApplyNameQualifierTo(NameContext& name_context, SemIR::LocationId loc_id,
+  auto ApplyNameQualifierTo(NameContext& name_context, SemIR::LocId loc_id,
                             SemIR::NameId name_id, bool is_unqualified) -> void;
 
   // Returns true if the context is in a state where it can resolve qualifiers.
   // Updates name_context as needed.
-  auto TryResolveQualifier(NameContext& name_context, SemIR::LocationId loc_id)
+  auto TryResolveQualifier(NameContext& name_context, SemIR::LocId loc_id)
       -> bool;
 
   // Updates the scope on name_context as needed. This is called after
diff --git a/toolchain/check/diagnostic_helpers.h b/toolchain/check/diagnostic_helpers.h
index cb572fb4ce39..32f3dbf4961c 100644
--- a/toolchain/check/diagnostic_helpers.h
+++ b/toolchain/check/diagnostic_helpers.h
@@ -14,31 +14,31 @@ namespace Carbon::Check {
 
 // Diagnostic locations produced by checking may be either a parse node
 // directly, or an inst ID which is later translated to a parse node.
-struct SemIRLocation {
+struct SemIRLoc {
   // NOLINTNEXTLINE(google-explicit-constructor)
-  SemIRLocation(SemIR::InstId inst_id)
+  SemIRLoc(SemIR::InstId inst_id)
       : inst_id(inst_id), is_inst_id(true), token_only(false) {}
 
   // NOLINTNEXTLINE(google-explicit-constructor)
-  SemIRLocation(Parse::NodeId node_id) : SemIRLocation(node_id, false) {}
+  SemIRLoc(Parse::NodeId node_id) : SemIRLoc(node_id, false) {}
 
   // NOLINTNEXTLINE(google-explicit-constructor)
-  SemIRLocation(SemIR::LocationId loc_id) : SemIRLocation(loc_id, false) {}
+  SemIRLoc(SemIR::LocId loc_id) : SemIRLoc(loc_id, false) {}
 
-  explicit SemIRLocation(SemIR::LocationId loc_id, bool token_only)
+  explicit SemIRLoc(SemIR::LocId loc_id, bool token_only)
       : loc_id(loc_id), is_inst_id(false), token_only(token_only) {}
 
   union {
     SemIR::InstId inst_id;
-    SemIR::LocationId loc_id;
+    SemIR::LocId loc_id;
   };
 
   bool is_inst_id;
   bool token_only;
 };
 
-inline auto TokenOnly(SemIR::LocationId loc_id) -> SemIRLocation {
-  return SemIRLocation(loc_id, true);
+inline auto TokenOnly(SemIR::LocId loc_id) -> SemIRLoc {
+  return SemIRLoc(loc_id, true);
 }
 
 // An integer value together with its type. The type is used to determine how to
diff --git a/toolchain/check/eval.cpp b/toolchain/check/eval.cpp
index 29a689c7c0ef..ecd0c99c9d54 100644
--- a/toolchain/check/eval.cpp
+++ b/toolchain/check/eval.cpp
@@ -287,14 +287,13 @@ static auto PerformAggregateIndex(Context& context, SemIR::Inst inst)
 }
 
 // Issues a diagnostic for a compile-time division by zero.
-static auto DiagnoseDivisionByZero(Context& context, SemIRLocation loc)
-    -> void {
+static auto DiagnoseDivisionByZero(Context& context, SemIRLoc loc) -> void {
   CARBON_DIAGNOSTIC(CompileTimeDivisionByZero, Error, "Division by zero.");
   context.emitter().Emit(loc, CompileTimeDivisionByZero);
 }
 
 // Performs a builtin unary integer -> integer operation.
-static auto PerformBuiltinUnaryIntOp(Context& context, SemIRLocation loc,
+static auto PerformBuiltinUnaryIntOp(Context& context, SemIRLoc loc,
                                      SemIR::BuiltinFunctionKind builtin_kind,
                                      SemIR::InstId arg_id)
     -> SemIR::ConstantId {
@@ -318,7 +317,7 @@ static auto PerformBuiltinUnaryIntOp(Context& context, SemIRLocation loc,
 }
 
 // Performs a builtin binary integer -> integer operation.
-static auto PerformBuiltinBinaryIntOp(Context& context, SemIRLocation loc,
+static auto PerformBuiltinBinaryIntOp(Context& context, SemIRLoc loc,
                                       SemIR::BuiltinFunctionKind builtin_kind,
                                       SemIR::InstId lhs_id,
                                       SemIR::InstId rhs_id)
@@ -416,8 +415,7 @@ static auto PerformBuiltinIntComparison(Context& context,
       Phase::Template);
 }
 
-static auto PerformBuiltinCall(Context& context, SemIRLocation loc,
-                               SemIR::Call call,
+static auto PerformBuiltinCall(Context& context, SemIRLoc loc, SemIR::Call call,
                                SemIR::BuiltinFunctionKind builtin_kind,
                                llvm::ArrayRef<SemIR::InstId> arg_ids,
                                Phase phase) -> SemIR::ConstantId {
@@ -463,7 +461,7 @@ static auto PerformBuiltinCall(Context& context, SemIRLocation loc,
   return SemIR::ConstantId::NotConstant;
 }
 
-static auto PerformCall(Context& context, SemIRLocation loc, SemIR::Call call)
+static auto PerformCall(Context& context, SemIRLoc loc, SemIR::Call call)
     -> SemIR::ConstantId {
   Phase phase = Phase::Template;
 
diff --git a/toolchain/check/function.cpp b/toolchain/check/function.cpp
index f37233623de0..dad23543f4aa 100644
--- a/toolchain/check/function.cpp
+++ b/toolchain/check/function.cpp
@@ -193,7 +193,7 @@ auto CheckFunctionTypeMatches(Context& context,
 
 // Checks to see if a structurally valid redeclaration is allowed in context.
 // These all still merge.
-static auto CheckIsAllowedRedecl(Context& context, SemIR::LocationId loc_id,
+static auto CheckIsAllowedRedecl(Context& context, SemIR::LocId loc_id,
                                  SemIR::Function& new_function,
                                  bool new_is_definition,
                                  SemIR::Function& prev_function,
@@ -253,7 +253,7 @@ static auto CheckIsAllowedRedecl(Context& context, SemIR::LocationId loc_id,
 
 // TODO: Detect conflicting cross-file declarations, as well as uses of imported
 // declarations followed by a redeclaration.
-auto MergeFunctionRedecl(Context& context, SemIR::LocationId loc_id,
+auto MergeFunctionRedecl(Context& context, SemIR::LocId loc_id,
                          SemIR::Function& new_function, bool new_is_definition,
                          SemIR::FunctionId prev_function_id,
                          bool prev_is_import) -> bool {
diff --git a/toolchain/check/function.h b/toolchain/check/function.h
index ceb6d351b1ff..d14e6bbd900d 100644
--- a/toolchain/check/function.h
+++ b/toolchain/check/function.h
@@ -28,7 +28,7 @@ auto CheckFunctionTypeMatches(Context& context,
 //
 // If merging is successful, updates the FunctionId on new_function and returns
 // true. Otherwise, returns false. Prints a diagnostic when appropriate.
-auto MergeFunctionRedecl(Context& context, SemIR::LocationId loc_id,
+auto MergeFunctionRedecl(Context& context, SemIR::LocId loc_id,
                          SemIR::Function& new_function, bool new_is_definition,
                          SemIR::FunctionId prev_function_id,
                          bool prev_is_imported) -> bool;
diff --git a/toolchain/check/handle_binding_pattern.cpp b/toolchain/check/handle_binding_pattern.cpp
index 67f54a2875b7..7023ac0b29d9 100644
--- a/toolchain/check/handle_binding_pattern.cpp
+++ b/toolchain/check/handle_binding_pattern.cpp
@@ -19,9 +19,8 @@ auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
   auto [name_node, name_id] = context.node_stack().PopNameWithNodeId();
 
   // Create the appropriate kind of binding for this pattern.
-  auto make_bind_name =
-      [&](SemIR::TypeId type_id,
-          SemIR::InstId value_id) -> SemIR::LocationIdAndInst {
+  auto make_bind_name = [&](SemIR::TypeId type_id,
+                            SemIR::InstId value_id) -> SemIR::LocIdAndInst {
     // TODO: Eventually the name will need to support associations with other
     // scopes, but right now we don't support qualified names here.
     auto bind_name_id = context.bind_names().Add(
diff --git a/toolchain/check/handle_expr_statement.cpp b/toolchain/check/handle_expr_statement.cpp
index 468e32dbba0d..37443ee053c7 100644
--- a/toolchain/check/handle_expr_statement.cpp
+++ b/toolchain/check/handle_expr_statement.cpp
@@ -15,7 +15,7 @@ static auto HandleDiscardedExpr(Context& context, SemIR::InstId expr_id)
   // If we discard an initializing expression, convert it to a value or
   // reference so that it has something to initialize.
   auto expr = context.insts().Get(expr_id);
-  Convert(context, context.insts().GetLocationId(expr_id), expr_id,
+  Convert(context, context.insts().GetLocId(expr_id), expr_id,
           {.kind = ConversionTarget::Discarded, .type_id = expr.type_id()});
 
   // TODO: This will eventually need to do some "do not discard" analysis.
diff --git a/toolchain/check/handle_index.cpp b/toolchain/check/handle_index.cpp
index 2b7a22d2291a..5b720778bf32 100644
--- a/toolchain/check/handle_index.cpp
+++ b/toolchain/check/handle_index.cpp
@@ -45,7 +45,7 @@ auto HandleIndexExpr(Context& context, Parse::IndexExprId node_id) -> bool {
   switch (operand_type_inst.kind()) {
     case SemIR::ArrayType::Kind: {
       auto array_type = operand_type_inst.As<SemIR::ArrayType>();
-      auto index_node_id = context.insts().GetLocationId(index_inst_id);
+      auto index_node_id = context.insts().GetLocId(index_inst_id);
       auto cast_index_id = ConvertToValueOfType(
           context, index_node_id, index_inst_id,
           context.GetBuiltinType(SemIR::BuiltinKind::IntType));
@@ -74,7 +74,7 @@ auto HandleIndexExpr(Context& context, Parse::IndexExprId node_id) -> bool {
     }
     case SemIR::TupleType::Kind: {
       SemIR::TypeId element_type_id = SemIR::TypeId::Error;
-      auto index_node_id = context.insts().GetLocationId(index_inst_id);
+      auto index_node_id = context.insts().GetLocId(index_inst_id);
       index_inst_id = ConvertToValueOfType(
           context, index_node_id, index_inst_id,
           context.GetBuiltinType(SemIR::BuiltinKind::IntType));
diff --git a/toolchain/check/handle_let.cpp b/toolchain/check/handle_let.cpp
index 7d5a0c17c426..fcba3ea5cea8 100644
--- a/toolchain/check/handle_let.cpp
+++ b/toolchain/check/handle_let.cpp
@@ -28,7 +28,7 @@ auto HandleLetInitializer(Context& context, Parse::LetInitializerId node_id)
 
 static auto BuildAssociatedConstantDecl(
     Context& context, Parse::LetDeclId node_id, SemIR::InstId pattern_id,
-    SemIR::LocationIdAndInst pattern, SemIR::InterfaceId interface_id) -> void {
+    SemIR::LocIdAndInst pattern, SemIR::InterfaceId interface_id) -> void {
   auto& interface_info = context.interfaces().Get(interface_id);
 
   auto binding_pattern = pattern.inst.TryAs<SemIR::BindSymbolicName>();
@@ -46,7 +46,7 @@ static auto BuildAssociatedConstantDecl(
   // declaration.
   auto name_id =
       context.bind_names().Get(binding_pattern->bind_name_id).name_id;
-  context.ReplaceLocationIdAndInstBeforeConstantUse(
+  context.ReplaceLocIdAndInstBeforeConstantUse(
       pattern_id, {node_id, SemIR::AssociatedConstantDecl{
                                 binding_pattern->type_id, name_id}});
   auto decl_id = pattern_id;
@@ -98,7 +98,7 @@ auto HandleLetDecl(Context& context, Parse::LetDeclId node_id) -> bool {
   }
   context.decl_state_stack().Pop(DeclState::Let);
 
-  auto pattern = context.insts().GetWithLocationId(pattern_id);
+  auto pattern = context.insts().GetWithLocId(pattern_id);
   auto interface_scope = context.GetCurrentScopeAs<SemIR::InterfaceDecl>();
 
   if (value_id) {
diff --git a/toolchain/check/handle_namespace.cpp b/toolchain/check/handle_namespace.cpp
index 50be9dddb308..c21ea6967fd3 100644
--- a/toolchain/check/handle_namespace.cpp
+++ b/toolchain/check/handle_namespace.cpp
@@ -40,7 +40,7 @@ auto HandleNamespace(Context& context, Parse::NamespaceId node_id) -> bool {
       // When the name conflict is an imported namespace, fill the location ID
       // so that future diagnostics point at this declaration.
       if (existing->import_id.is_valid() &&
-          !context.insts().GetLocationId(existing_inst_id).is_valid()) {
+          !context.insts().GetLocId(existing_inst_id).is_valid()) {
         context.SetNamespaceNodeId(existing_inst_id, node_id);
       }
     } else {
diff --git a/toolchain/check/handle_variable.cpp b/toolchain/check/handle_variable.cpp
index d04dd6628f84..5770d091b69d 100644
--- a/toolchain/check/handle_variable.cpp
+++ b/toolchain/check/handle_variable.cpp
@@ -55,7 +55,7 @@ auto HandleVariableDecl(Context& context, Parse::VariableDeclId node_id)
     // Form a corresponding name in the current context, and bind the name to
     // the variable.
     auto name_context = context.decl_name_stack().MakeUnqualifiedName(
-        context.insts().GetLocationId(value_id),
+        context.insts().GetLocId(value_id),
         context.bind_names().Get(bind_name->bind_name_id).name_id);
     context.decl_name_stack().AddNameToLookup(name_context, value_id);
     value_id = bind_name->value_id;
@@ -63,7 +63,7 @@ auto HandleVariableDecl(Context& context, Parse::VariableDeclId node_id)
                  context.insts().TryGetAs<SemIR::FieldDecl>(value_id)) {
     // Introduce the field name into the class.
     auto name_context = context.decl_name_stack().MakeUnqualifiedName(
-        context.insts().GetLocationId(value_id), field_decl->name_id);
+        context.insts().GetLocId(value_id), field_decl->name_id);
     context.decl_name_stack().AddNameToLookup(name_context, value_id);
   }
   // TODO: Handle other kinds of pattern.
diff --git a/toolchain/check/import_ref.cpp b/toolchain/check/import_ref.cpp
index 7277ad8534eb..b9aebe896dc0 100644
--- a/toolchain/check/import_ref.cpp
+++ b/toolchain/check/import_ref.cpp
@@ -158,7 +158,7 @@ class ImportRefResolver {
     return initial_work < work_stack_.size();
   }
 
-  auto AddImportIRInst(SemIR::InstId inst_id) -> SemIR::LocationId {
+  auto AddImportIRInst(SemIR::InstId inst_id) -> SemIR::LocId {
     return context_.import_ir_insts().Add(
         {.ir_id = import_ir_id_, .inst_id = inst_id});
   }
@@ -274,10 +274,9 @@ class ImportRefResolver {
         }
       }
       if (addr_inst) {
-        new_param_id =
-            context_.AddInstInNoBlock(SemIR::LocationIdAndInst::Untyped(
-                AddImportIRInst(ref_id),
-                SemIR::AddrPattern{type_id, new_param_id}));
+        new_param_id = context_.AddInstInNoBlock(SemIR::LocIdAndInst::Untyped(
+            AddImportIRInst(ref_id),
+            SemIR::AddrPattern{type_id, new_param_id}));
       }
       new_param_refs.push_back(new_param_id);
     }
@@ -486,7 +485,7 @@ class ImportRefResolver {
     }
 
     // Import the instruction in order to update contained base_type_id.
-    auto inst_id = context_.AddInstInNoBlock(SemIR::LocationIdAndInst::Untyped(
+    auto inst_id = context_.AddInstInNoBlock(SemIR::LocIdAndInst::Untyped(
         AddImportIRInst(import_inst_id),
         SemIR::BaseDecl{context_.GetTypeIdForTypeConstant(type_const_id),
                         context_.GetTypeIdForTypeConstant(base_type_const_id),
@@ -532,7 +531,7 @@ class ImportRefResolver {
         SemIR::ClassDecl{SemIR::TypeId::Invalid, SemIR::ClassId::Invalid,
                          SemIR::InstBlockId::Empty};
     auto class_decl_id =
-        context_.AddPlaceholderInst(SemIR::LocationIdAndInst::Untyped(
+        context_.AddPlaceholderInst(SemIR::LocIdAndInst::Untyped(
             AddImportIRInst(import_class.decl_id), class_decl));
     // Regardless of whether ClassDecl is a complete type, we first need an
     // incomplete type so that any references have something to point at.
@@ -664,7 +663,7 @@ class ImportRefResolver {
     if (HasNewWork(initial_work)) {
       return ResolveResult::Retry();
     }
-    auto inst_id = context_.AddInstInNoBlock(SemIR::LocationIdAndInst::Untyped(
+    auto inst_id = context_.AddInstInNoBlock(SemIR::LocIdAndInst::Untyped(
         AddImportIRInst(import_inst_id),
         SemIR::FieldDecl{context_.GetTypeIdForTypeConstant(const_id),
                          GetLocalNameId(inst.name_id), inst.index}));
@@ -699,7 +698,7 @@ class ImportRefResolver {
         context_.GetTypeIdForTypeConstant(type_const_id),
         SemIR::FunctionId::Invalid, SemIR::InstBlockId::Empty};
     auto function_decl_id =
-        context_.AddPlaceholderInstInNoBlock(SemIR::LocationIdAndInst::Untyped(
+        context_.AddPlaceholderInstInNoBlock(SemIR::LocIdAndInst::Untyped(
             AddImportIRInst(function.decl_id), function_decl));
 
     auto new_return_type_id =
@@ -737,7 +736,7 @@ class ImportRefResolver {
                                                SemIR::InterfaceId::Invalid,
                                                SemIR::InstBlockId::Empty};
     auto interface_decl_id =
-        context_.AddPlaceholderInst(SemIR::LocationIdAndInst::Untyped(
+        context_.AddPlaceholderInst(SemIR::LocIdAndInst::Untyped(
             AddImportIRInst(import_interface.decl_id), interface_decl));
 
     // Start with an incomplete interface.
diff --git a/toolchain/check/interface.cpp b/toolchain/check/interface.cpp
index fa774ce81259..6538fa15513b 100644
--- a/toolchain/check/interface.cpp
+++ b/toolchain/check/interface.cpp
@@ -29,7 +29,7 @@ auto BuildAssociatedEntity(Context& context, SemIR::InterfaceId interface_id,
   // not the declaration itself.
   auto type_id = context.GetAssociatedEntityType(
       interface_id, context.insts().Get(decl_id).type_id());
-  return context.AddInst({context.insts().GetLocationId(decl_id),
+  return context.AddInst({context.insts().GetLocId(decl_id),
                           SemIR::AssociatedEntity{type_id, index, decl_id}});
 }
 
diff --git a/toolchain/check/merge.cpp b/toolchain/check/merge.cpp
index 9b7720bebc6d..7e93d92ee573 100644
--- a/toolchain/check/merge.cpp
+++ b/toolchain/check/merge.cpp
@@ -66,7 +66,7 @@ auto MergeImportRef(Context& context, SemIR::InstId new_inst_id,
       auto prev_fn_id = prev_inst->As<SemIR::FunctionDecl>().function_id;
       // TODO: May need to "spoil" the new function to prevent it from being
       // emitted, since it will already be added.
-      MergeFunctionRedecl(context, context.insts().GetLocationId(new_inst_id),
+      MergeFunctionRedecl(context, context.insts().GetLocId(new_inst_id),
                           new_fn,
                           /*new_is_definition=*/false, prev_fn_id,
                           /*prev_is_imported=*/true);
diff --git a/toolchain/check/modifiers.cpp b/toolchain/check/modifiers.cpp
index 44ce316a3ff7..6099a1021f2b 100644
--- a/toolchain/check/modifiers.cpp
+++ b/toolchain/check/modifiers.cpp
@@ -11,7 +11,7 @@ namespace Carbon::Check {
 static auto ReportNotAllowed(Context& context, Parse::NodeId modifier_node,
                              Lex::TokenKind decl_kind,
                              llvm::StringRef context_string,
-                             SemIR::LocationId context_loc_id) -> void {
+                             SemIR::LocId context_loc_id) -> void {
   CARBON_DIAGNOSTIC(ModifierNotAllowedOn, Error,
                     "`{0}` not allowed on `{1}` declaration{2}.",
                     Lex::TokenKind, Lex::TokenKind, std::string);
@@ -41,7 +41,7 @@ static auto ModifierOrderAsSet(ModifierOrder order) -> KeywordModifierSet {
 auto ForbidModifiersOnDecl(Context& context, KeywordModifierSet forbidden,
                            Lex::TokenKind decl_kind,
                            llvm::StringRef context_string,
-                           SemIR::LocationId context_loc_id) -> void {
+                           SemIR::LocId context_loc_id) -> void {
   auto& s = context.decl_state_stack().innermost();
   auto not_allowed = s.modifier_set & forbidden;
   if (!not_allowed) {
@@ -121,12 +121,12 @@ auto CheckMethodModifiersOnFunction(Context& context,
       if (inheritance_kind == SemIR::Class::Final) {
         ForbidModifiersOnDecl(context, KeywordModifierSet::Virtual, decl_kind,
                               " in a non-abstract non-base `class` definition",
-                              context.insts().GetLocationId(target_id));
+                              context.insts().GetLocId(target_id));
       }
       if (inheritance_kind != SemIR::Class::Abstract) {
         ForbidModifiersOnDecl(context, KeywordModifierSet::Abstract, decl_kind,
                               " in a non-abstract `class` definition",
-                              context.insts().GetLocationId(target_id));
+                              context.insts().GetLocId(target_id));
       }
       return;
     }
diff --git a/toolchain/check/modifiers.h b/toolchain/check/modifiers.h
index b8bc3b06d337..39a2483cdf94 100644
--- a/toolchain/check/modifiers.h
+++ b/toolchain/check/modifiers.h
@@ -29,10 +29,11 @@ auto CheckMethodModifiersOnFunction(Context& context,
 // `context_string` (and optional `context_loc_id`) specifying the context in
 // which those modifiers are forbidden.
 // TODO: Take another look at diagnostic phrasing for callers.
-auto ForbidModifiersOnDecl(
-    Context& context, KeywordModifierSet forbidden, Lex::TokenKind decl_kind,
-    llvm::StringRef context_string,
-    SemIR::LocationId context_loc_id = SemIR::LocationId::Invalid) -> void;
+auto ForbidModifiersOnDecl(Context& context, KeywordModifierSet forbidden,
+                           Lex::TokenKind decl_kind,
+                           llvm::StringRef context_string,
+                           SemIR::LocId context_loc_id = SemIR::LocId::Invalid)
+    -> void;
 
 // Reports a diagnostic (using `decl_kind`) if modifiers on this declaration are
 // not in `allowed`. Updates the declaration state in
diff --git a/toolchain/check/pending_block.h b/toolchain/check/pending_block.h
index 39e639a92749..a99ceae6f341 100644
--- a/toolchain/check/pending_block.h
+++ b/toolchain/check/pending_block.h
@@ -39,7 +39,7 @@ class PendingBlock {
     size_t size_;
   };
 
-  auto AddInst(SemIR::LocationIdAndInst loc_id_and_inst) -> SemIR::InstId {
+  auto AddInst(SemIR::LocIdAndInst loc_id_and_inst) -> SemIR::InstId {
     auto inst_id = context_.AddInstInNoBlock(loc_id_and_inst);
     insts_.push_back(inst_id);
     return inst_id;
@@ -56,24 +56,24 @@ class PendingBlock {
   // Replace the instruction at target_id with the instructions in this block.
   // The new value for target_id should be value_id.
   auto MergeReplacing(SemIR::InstId target_id, SemIR::InstId value_id) -> void {
-    auto value = context_.insts().GetWithLocationId(value_id);
+    auto value = context_.insts().GetWithLocId(value_id);
 
     // There are three cases here:
 
     if (insts_.empty()) {
       // 1) The block is empty. Replace `target_id` with an empty splice
       // pointing at `value_id`.
-      context_.ReplaceLocationIdAndInstBeforeConstantUse(
+      context_.ReplaceLocIdAndInstBeforeConstantUse(
           target_id, {value.loc_id,
                       SemIR::SpliceBlock{value.inst.type_id(),
                                          SemIR::InstBlockId::Empty, value_id}});
     } else if (insts_.size() == 1 && insts_[0] == value_id) {
       // 2) The block is {value_id}. Replace `target_id` with the instruction
       // referred to by `value_id`. This is intended to be the common case.
-      context_.ReplaceLocationIdAndInstBeforeConstantUse(target_id, value);
+      context_.ReplaceLocIdAndInstBeforeConstantUse(target_id, value);
     } else {
       // 3) Anything else: splice it into the IR, replacing `target_id`.
-      context_.ReplaceLocationIdAndInstBeforeConstantUse(
+      context_.ReplaceLocIdAndInstBeforeConstantUse(
           target_id,
           {value.loc_id,
            SemIR::SpliceBlock{value.inst.type_id(),
diff --git a/toolchain/diagnostics/check_diagnostics.py b/toolchain/diagnostics/check_diagnostics.py
index 4c4db33237dc..6014ce9318cf 100755
--- a/toolchain/diagnostics/check_diagnostics.py
+++ b/toolchain/diagnostics/check_diagnostics.py
@@ -26,7 +26,7 @@ from typing import Dict, List, NamedTuple, Set
 IGNORED = set(["MyDiagnostic", "TestDiagnostic", "TestDiagnosticNote"])
 
 
-class Location(NamedTuple):
+class Loc(NamedTuple):
     """A location for a diagnostic."""
 
     def __str__(self) -> str:
@@ -49,7 +49,7 @@ def load_diagnostic_kind() -> Set[str]:
 
 def load_diagnostic_uses_in(
     path: Path,
-) -> Dict[str, List[Location]]:
+) -> Dict[str, List[Loc]]:
     """Returns the path's CARBON_DIAGNOSTIC uses."""
     content = path.read_text()
 
@@ -57,18 +57,18 @@ def load_diagnostic_uses_in(
     line = 1
     line_offset = 0
 
-    found: Dict[str, List[Location]] = collections.defaultdict(lambda: [])
+    found: Dict[str, List[Loc]] = collections.defaultdict(lambda: [])
     for m in re.finditer(r"CARBON_DIAGNOSTIC\(\s*(\w+),", content):
         diag = m.group(1)
         if diag in IGNORED:
             continue
         line += content.count("\n", line_offset, m.start())
         line_offset = m.start()
-        found[diag].append(Location(path, line))
+        found[diag].append(Loc(path, line))
     return found
 
 
-def load_diagnostic_uses() -> Dict[str, List[Location]]:
+def load_diagnostic_uses() -> Dict[str, List[Loc]]:
     """Returns all CARBON_DIAGNOSTIC uses."""
     globs = itertools.chain(
         *[Path("toolchain").glob(f"**/*.{ext}") for ext in ("h", "cpp")]
@@ -76,14 +76,14 @@ def load_diagnostic_uses() -> Dict[str, List[Location]]:
     with futures.ThreadPoolExecutor() as exec:
         results = exec.map(load_diagnostic_uses_in, globs)
 
-    found: Dict[str, List[Location]] = collections.defaultdict(lambda: [])
+    found: Dict[str, List[Loc]] = collections.defaultdict(lambda: [])
     for result in results:
         for diag, locations in result.items():
             found[diag].extend(locations)
     return found
 
 
-def check_uniqueness(uses: Dict[str, List[Location]]) -> bool:
+def check_uniqueness(uses: Dict[str, List[Loc]]) -> bool:
     """If any diagnostic is non-unique, prints an error and returns true."""
     has_errors = False
     for diag in sorted(uses.keys()):
@@ -95,7 +95,7 @@ def check_uniqueness(uses: Dict[str, List[Location]]) -> bool:
     return has_errors
 
 
-def check_unused(decls: Set[str], uses: Dict[str, List[Location]]) -> bool:
+def check_unused(decls: Set[str], uses: Dict[str, List[Loc]]) -> bool:
     """If any diagnostic is unused, prints an error and returns true."""
     unused = decls.difference(uses.keys())
     if not unused:
diff --git a/toolchain/diagnostics/diagnostic.h b/toolchain/diagnostics/diagnostic.h
index dff96f8d51bb..11d35adf462c 100644
--- a/toolchain/diagnostics/diagnostic.h
+++ b/toolchain/diagnostics/diagnostic.h
@@ -42,10 +42,10 @@ enum class DiagnosticLevel : int8_t {
           ::Carbon::DiagnosticKind::DiagnosticName,           \
           ::Carbon::DiagnosticLevel::Level, Format)
 
-// A location for a diagnostic in a file. The lifetime of a DiagnosticLocation
+// A location for a diagnostic in a file. The lifetime of a DiagnosticLoc
 // is required to be less than SourceBuffer that it refers to due to the
 // contained filename and line references.
-struct DiagnosticLocation {
+struct DiagnosticLoc {
   // Name of the file or buffer that this diagnostic refers to.
   llvm::StringRef filename;
   // A reference to the line of the error.
@@ -68,7 +68,7 @@ struct DiagnosticMessage {
   DiagnosticLevel level;
 
   // The calculated location of the diagnostic.
-  DiagnosticLocation location;
+  DiagnosticLoc loc;
 
   // The diagnostic's format string. This, along with format_args, will be
   // passed to format_fn.
diff --git a/toolchain/diagnostics/diagnostic_consumer.cpp b/toolchain/diagnostics/diagnostic_consumer.cpp
index 0511ea344522..c8bed5136eaf 100644
--- a/toolchain/diagnostics/diagnostic_consumer.cpp
+++ b/toolchain/diagnostics/diagnostic_consumer.cpp
@@ -17,11 +17,11 @@ auto StreamDiagnosticConsumer::HandleDiagnostic(Diagnostic diagnostic) -> void {
   }
 
   for (const auto& message : diagnostic.messages) {
-    *stream_ << message.location.filename;
-    if (message.location.line_number > 0) {
-      *stream_ << ":" << message.location.line_number;
-      if (message.location.column_number > 0) {
-        *stream_ << ":" << message.location.column_number;
+    *stream_ << message.loc.filename;
+    if (message.loc.line_number > 0) {
+      *stream_ << ":" << message.loc.line_number;
+      if (message.loc.column_number > 0) {
+        *stream_ << ":" << message.loc.column_number;
       }
     }
     *stream_ << ": ";
@@ -29,18 +29,18 @@ auto StreamDiagnosticConsumer::HandleDiagnostic(Diagnostic diagnostic) -> void {
       *stream_ << "ERROR: ";
     }
     *stream_ << message.format_fn(message) << "\n";
-    if (message.location.column_number > 0) {
-      *stream_ << message.location.line << "\n";
-      stream_->indent(message.location.column_number - 1);
+    if (message.loc.column_number > 0) {
+      *stream_ << message.loc.line << "\n";
+      stream_->indent(message.loc.column_number - 1);
       *stream_ << "^";
-      int underline_length = std::max(0, message.location.length - 1);
+      int underline_length = std::max(0, message.loc.length - 1);
       // We want to ensure that we don't underline past the end of the line in
       // case of a multiline token.
       // TODO: revisit this once we can reference multiple ranges on multiple
       // lines in a single diagnostic message.
       underline_length = std::min(
-          underline_length, static_cast<int32_t>(message.location.line.size()) -
-                                message.location.column_number);
+          underline_length, static_cast<int32_t>(message.loc.line.size()) -
+                                message.loc.column_number);
       for (int i = 0; i < underline_length; ++i) {
         *stream_ << "~";
       }
diff --git a/toolchain/diagnostics/diagnostic_converter.h b/toolchain/diagnostics/diagnostic_converter.h
index e043ce56f9d3..200c0c10b194 100644
--- a/toolchain/diagnostics/diagnostic_converter.h
+++ b/toolchain/diagnostics/diagnostic_converter.h
@@ -12,21 +12,21 @@ namespace Carbon {
 
 // An interface that can convert some representation of a location into a
 // diagnostic location.
-template <typename LocationT>
+template <typename LocT>
 class DiagnosticConverter {
  public:
-  // Callback type used to report context messages from ConvertLocation.
-  // Note that the first parameter type is DiagnosticLocation rather than
-  // LocationT, because ConvertLocation must not recurse.
+  // Callback type used to report context messages from ConvertLoc.
+  // Note that the first parameter type is DiagnosticLoc rather than
+  // LocT, because ConvertLoc must not recurse.
   using ContextFnT = llvm::function_ref<void(
-      DiagnosticLocation, const Internal::DiagnosticBase<>&)>;
+      DiagnosticLoc, const Internal::DiagnosticBase<>&)>;
 
   virtual ~DiagnosticConverter() = default;
 
-  // Converts a LocationT to a DiagnosticLocation. ConvertLocation may invoke
+  // Converts a LocT to a DiagnosticLoc. ConvertLoc may invoke
   // context_fn to provide context messages.
-  virtual auto ConvertLocation(LocationT loc, ContextFnT context_fn) const
-      -> DiagnosticLocation = 0;
+  virtual auto ConvertLoc(LocT loc, ContextFnT context_fn) const
+      -> DiagnosticLoc = 0;
 
   // Converts arg types as needed. Not all uses require conversion, so the
   // default returns the argument unchanged.
diff --git a/toolchain/diagnostics/diagnostic_emitter.h b/toolchain/diagnostics/diagnostic_emitter.h
index 6ca20c3761b1..cb0481393f72 100644
--- a/toolchain/diagnostics/diagnostic_emitter.h
+++ b/toolchain/diagnostics/diagnostic_emitter.h
@@ -30,7 +30,7 @@ using NoTypeDeduction = std::type_identity_t<Arg>;
 
 }  // namespace Internal
 
-template <typename LocationT, typename AnnotateFn>
+template <typename LocT, typename AnnotateFn>
 class DiagnosticAnnotationScope;
 
 // Manages the creation of reports, the testing if diagnostics are enabled, and
@@ -41,7 +41,7 @@ class DiagnosticAnnotationScope;
 // convenient for them, such as a position within a buffer when lexing, a token
 // when parsing, or a parse tree node when type-checking, and to allow unit
 // tests to be decoupled from any concrete location representation.
-template <typename LocationT>
+template <typename LocT>
 class DiagnosticEmitter {
  public:
   // A builder-pattern type to provide a fluent interface for constructing
@@ -60,12 +60,12 @@ class DiagnosticEmitter {
     // The API mirrors the main emission API: `DiagnosticEmitter::Emit`.
     // For the expected usage see the builder API: `DiagnosticEmitter::Build`.
     template <typename... Args>
-    auto Note(LocationT location,
+    auto Note(LocT loc,
               const Internal::DiagnosticBase<Args...>& diagnostic_base,
               Internal::NoTypeDeduction<Args>... args) -> DiagnosticBuilder& {
       CARBON_CHECK(diagnostic_base.Level == DiagnosticLevel::Note)
           << static_cast<int>(diagnostic_base.Level);
-      AddMessage(location, diagnostic_base, {emitter_->MakeAny<Args>(args)...});
+      AddMessage(loc, diagnostic_base, {emitter_->MakeAny<Args>(args)...});
       return *this;
     }
 
@@ -80,47 +80,46 @@ class DiagnosticEmitter {
     }
 
    private:
-    friend class DiagnosticEmitter<LocationT>;
+    friend class DiagnosticEmitter<LocT>;
 
     template <typename... Args>
     explicit DiagnosticBuilder(
-        DiagnosticEmitter<LocationT>* emitter, LocationT location,
+        DiagnosticEmitter<LocT>* emitter, LocT loc,
         const Internal::DiagnosticBase<Args...>& diagnostic_base,
         llvm::SmallVector<llvm::Any> args)
         : emitter_(emitter), diagnostic_({.level = diagnostic_base.Level}) {
-      AddMessage(location, diagnostic_base, std::move(args));
+      AddMessage(loc, diagnostic_base, std::move(args));
       CARBON_CHECK(diagnostic_base.Level != DiagnosticLevel::Note);
     }
 
     // Adds a message to the diagnostic, handling conversion of the location and
     // arguments.
     template <typename... Args>
-    auto AddMessage(LocationT location,
+    auto AddMessage(LocT loc,
                     const Internal::DiagnosticBase<Args...>& diagnostic_base,
                     llvm::SmallVector<llvm::Any> args) -> void {
-      AddMessageWithDiagnosticLocation(
-          emitter_->converter_->ConvertLocation(
-              location,
-              [&](DiagnosticLocation location,
+      AddMessageWithDiagnosticLoc(
+          emitter_->converter_->ConvertLoc(
+              loc,
+              [&](DiagnosticLoc loc,
                   const Internal::DiagnosticBase<>& diagnostic_base) {
-                AddMessageWithDiagnosticLocation(location, diagnostic_base,
-                                                 args);
+                AddMessageWithDiagnosticLoc(loc, diagnostic_base, args);
               }),
           diagnostic_base, args);
     }
 
     // Adds a message to the diagnostic, handling conversion of the arguments. A
-    // DiagnosticLocation must be provided instead of a LocationT in order to
+    // DiagnosticLoc must be provided instead of a LocT in order to
     // avoid potential recursion.
     template <typename... Args>
-    auto AddMessageWithDiagnosticLocation(
-        DiagnosticLocation location,
+    auto AddMessageWithDiagnosticLoc(
+        DiagnosticLoc loc,
         const Internal::DiagnosticBase<Args...>& diagnostic_base,
         llvm::SmallVector<llvm::Any> args) {
       diagnostic_.messages.emplace_back(DiagnosticMessage{
           .kind = diagnostic_base.Kind,
           .level = diagnostic_base.Level,
-          .location = location,
+          .loc = loc,
           .format = diagnostic_base.Format,
           .format_args = std::move(args),
           .format_fn = [](const DiagnosticMessage& message) -> std::string {
@@ -145,13 +144,13 @@ class DiagnosticEmitter {
               message.format_args[N])...);
     }
 
-    DiagnosticEmitter<LocationT>* emitter_;
+    DiagnosticEmitter<LocT>* emitter_;
     Diagnostic diagnostic_;
   };
 
   // The `converter` and `consumer` are required to outlive the diagnostic
   // emitter.
-  explicit DiagnosticEmitter(DiagnosticConverter<LocationT>& converter,
+  explicit DiagnosticEmitter(DiagnosticConverter<LocT>& converter,
                              DiagnosticConsumer& consumer)
       : converter_(&converter), consumer_(&consumer) {}
   ~DiagnosticEmitter() = default;
@@ -161,24 +160,22 @@ class DiagnosticEmitter {
   // When passing arguments, they may be buffered. As a consequence, lifetimes
   // may outlive the `Emit` call.
   template <typename... Args>
-  auto Emit(LocationT location,
-            const Internal::DiagnosticBase<Args...>& diagnostic_base,
+  auto Emit(LocT loc, const Internal::DiagnosticBase<Args...>& diagnostic_base,
             Internal::NoTypeDeduction<Args>... args) -> void {
-    DiagnosticBuilder(this, location, diagnostic_base, {MakeAny<Args>(args)...})
+    DiagnosticBuilder(this, loc, diagnostic_base, {MakeAny<Args>(args)...})
         .Emit();
   }
 
   // A fluent interface for building a diagnostic and attaching notes for added
   // context or information. For example:
   //
-  //   emitter_.Build(location1, MyDiagnostic)
-  //     .Note(location2, MyDiagnosticNote)
+  //   emitter_.Build(loc1, MyDiagnostic)
+  //     .Note(loc2, MyDiagnosticNote)
   //     .Emit();
   template <typename... Args>
-  auto Build(LocationT location,
-             const Internal::DiagnosticBase<Args...>& diagnostic_base,
+  auto Build(LocT loc, const Internal::DiagnosticBase<Args...>& diagnostic_base,
              Internal::NoTypeDeduction<Args>... args) -> DiagnosticBuilder {
-    return DiagnosticBuilder(this, location, diagnostic_base,
+    return DiagnosticBuilder(this, loc, diagnostic_base,
                              {MakeAny<Args>(args)...});
   }
 
@@ -195,10 +192,10 @@ class DiagnosticEmitter {
     return converted;
   }
 
-  template <typename LocT, typename AnnotateFn>
+  template <typename OtherLocT, typename AnnotateFn>
   friend class DiagnosticAnnotationScope;
 
-  DiagnosticConverter<LocationT>* converter_;
+  DiagnosticConverter<LocT>* converter_;
   DiagnosticConsumer* consumer_;
   llvm::SmallVector<llvm::function_ref<auto(DiagnosticBuilder& builder)->void>>
       annotate_fns_;
@@ -211,10 +208,10 @@ class DiagnosticEmitter {
 // `DiagnosticBuilder& builder` for any diagnostic that is emitted through the
 // given emitter. That function can annotate the diagnostic by calling
 // `builder.Note` to add notes.
-template <typename LocationT, typename AnnotateFn>
+template <typename LocT, typename AnnotateFn>
 class DiagnosticAnnotationScope {
  public:
-  DiagnosticAnnotationScope(DiagnosticEmitter<LocationT>* emitter,
+  DiagnosticAnnotationScope(DiagnosticEmitter<LocT>* emitter,
                             AnnotateFn annotate)
       : emitter_(emitter), annotate_(std::move(annotate)) {
     emitter_->annotate_fns_.push_back(annotate_);
@@ -222,15 +219,14 @@ class DiagnosticAnnotationScope {
   ~DiagnosticAnnotationScope() { emitter_->annotate_fns_.pop_back(); }
 
  private:
-  DiagnosticEmitter<LocationT>* emitter_;
+  DiagnosticEmitter<LocT>* emitter_;
   // Make a copy of the annotation function to ensure that it lives long enough.
   AnnotateFn annotate_;
 };
 
-template <typename LocationT, typename AnnotateFn>
-DiagnosticAnnotationScope(DiagnosticEmitter<LocationT>* emitter,
-                          AnnotateFn annotate)
-    -> DiagnosticAnnotationScope<LocationT, AnnotateFn>;
+template <typename LocT, typename AnnotateFn>
+DiagnosticAnnotationScope(DiagnosticEmitter<LocT>* emitter, AnnotateFn annotate)
+    -> DiagnosticAnnotationScope<LocT, AnnotateFn>;
 
 }  // namespace Carbon
 
diff --git a/toolchain/diagnostics/diagnostic_emitter_test.cpp b/toolchain/diagnostics/diagnostic_emitter_test.cpp
index b68fdb0970fe..50ad5a0536ee 100644
--- a/toolchain/diagnostics/diagnostic_emitter_test.cpp
+++ b/toolchain/diagnostics/diagnostic_emitter_test.cpp
@@ -18,8 +18,8 @@ using ::Carbon::Testing::IsSingleDiagnostic;
 using testing::ElementsAre;
 
 struct FakeDiagnosticConverter : DiagnosticConverter<int> {
-  auto ConvertLocation(int n, ContextFnT /*context_fn*/) const
-      -> DiagnosticLocation override {
+  auto ConvertLoc(int n, ContextFnT /*context_fn*/) const
+      -> DiagnosticLoc override {
     return {.line_number = 1, .column_number = n};
   }
 };
diff --git a/toolchain/diagnostics/mocks.cpp b/toolchain/diagnostics/mocks.cpp
index 8ca096c6c7fa..9383c831d3e7 100644
--- a/toolchain/diagnostics/mocks.cpp
+++ b/toolchain/diagnostics/mocks.cpp
@@ -10,9 +10,9 @@ void PrintTo(const Diagnostic& diagnostic, std::ostream* os) {
   *os << "Diagnostic{";
   PrintTo(diagnostic.level, os);
   for (const auto& message : diagnostic.messages) {
-    *os << ", {" << message.location.filename << ":"
-        << message.location.line_number << ":" << message.location.column_number
-        << ", \"" << message.format_fn(message) << "}";
+    *os << ", {" << message.loc.filename << ":" << message.loc.line_number
+        << ":" << message.loc.column_number << ", \""
+        << message.format_fn(message) << "}";
   }
   *os << "\"}";
 }
diff --git a/toolchain/diagnostics/mocks.h b/toolchain/diagnostics/mocks.h
index dbf77ebf17f6..d8a01fde2acd 100644
--- a/toolchain/diagnostics/mocks.h
+++ b/toolchain/diagnostics/mocks.h
@@ -31,15 +31,14 @@ inline auto IsDiagnosticMessage(testing::Matcher<DiagnosticKind> kind,
     -> testing::Matcher<DiagnosticMessage> {
   using testing::AllOf;
   using testing::Field;
-  return AllOf(
-      Field("kind", &DiagnosticMessage::kind, kind),
-      Field("level", &DiagnosticMessage::level, level),
-      Field(&DiagnosticMessage::location,
-            AllOf(Field("line_number", &DiagnosticLocation::line_number,
-                        line_number),
-                  Field("column_number", &DiagnosticLocation::column_number,
-                        column_number))),
-      IsDiagnosticMessageString(message));
+  return AllOf(Field("kind", &DiagnosticMessage::kind, kind),
+               Field("level", &DiagnosticMessage::level, level),
+               Field(&DiagnosticMessage::loc,
+                     AllOf(Field("line_number", &DiagnosticLoc::line_number,
+                                 line_number),
+                           Field("column_number", &DiagnosticLoc::column_number,
+                                 column_number))),
+               IsDiagnosticMessageString(message));
 }
 
 inline auto IsDiagnostic(
diff --git a/toolchain/diagnostics/null_diagnostics.h b/toolchain/diagnostics/null_diagnostics.h
index 5e9c6f8e3f45..4f73ec8a6f71 100644
--- a/toolchain/diagnostics/null_diagnostics.h
+++ b/toolchain/diagnostics/null_diagnostics.h
@@ -9,13 +9,12 @@
 
 namespace Carbon {
 
-template <typename LocationT>
-inline auto NullDiagnosticConverter() -> DiagnosticConverter<LocationT>& {
-  struct Converter : public DiagnosticConverter<LocationT> {
-    auto ConvertLocation(
-        LocationT /*loc*/,
-        DiagnosticConverter<LocationT>::ContextFnT /*context_fn*/) const
-        -> DiagnosticLocation override {
+template <typename LocT>
+inline auto NullDiagnosticConverter() -> DiagnosticConverter<LocT>& {
+  struct Converter : public DiagnosticConverter<LocT> {
+    auto ConvertLoc(LocT /*loc*/,
+                    DiagnosticConverter<LocT>::ContextFnT /*context_fn*/) const
+        -> DiagnosticLoc override {
       return {};
     }
   };
@@ -31,10 +30,10 @@ inline auto NullDiagnosticConsumer() -> DiagnosticConsumer& {
   return *consumer;
 }
 
-template <typename LocationT>
-inline auto NullDiagnosticEmitter() -> DiagnosticEmitter<LocationT>& {
-  static auto* emitter = new DiagnosticEmitter<LocationT>(
-      NullDiagnosticConverter<LocationT>(), NullDiagnosticConsumer());
+template <typename LocT>
+inline auto NullDiagnosticEmitter() -> DiagnosticEmitter<LocT>& {
+  static auto* emitter = new DiagnosticEmitter<LocT>(
+      NullDiagnosticConverter<LocT>(), NullDiagnosticConsumer());
   return *emitter;
 }
 
diff --git a/toolchain/diagnostics/sorting_diagnostic_consumer.h b/toolchain/diagnostics/sorting_diagnostic_consumer.h
index 79175ea936ec..35a307a97b74 100644
--- a/toolchain/diagnostics/sorting_diagnostic_consumer.h
+++ b/toolchain/diagnostics/sorting_diagnostic_consumer.h
@@ -35,8 +35,8 @@ class SortingDiagnosticConsumer : public DiagnosticConsumer {
   void Flush() override {
     llvm::stable_sort(diagnostics_,
                       [](const Diagnostic& lhs, const Diagnostic& rhs) {
-                        const auto& lhs_loc = lhs.messages[0].location;
-                        const auto& rhs_loc = rhs.messages[0].location;
+                        const auto& lhs_loc = lhs.messages[0].loc;
+                        const auto& rhs_loc = rhs.messages[0].loc;
                         return std::tie(lhs_loc.filename, lhs_loc.line_number,
                                         lhs_loc.column_number) <
                                std::tie(rhs_loc.filename, rhs_loc.line_number,
diff --git a/toolchain/diagnostics/sorting_diagnostic_consumer_test.cpp b/toolchain/diagnostics/sorting_diagnostic_consumer_test.cpp
index ba3337145c04..d97f535b063f 100644
--- a/toolchain/diagnostics/sorting_diagnostic_consumer_test.cpp
+++ b/toolchain/diagnostics/sorting_diagnostic_consumer_test.cpp
@@ -19,9 +19,9 @@ using ::testing::InSequence;
 
 CARBON_DIAGNOSTIC(TestDiagnostic, Error, "{0}", llvm::StringLiteral);
 
-struct FakeDiagnosticConverter : DiagnosticConverter<DiagnosticLocation> {
-  auto ConvertLocation(DiagnosticLocation loc, ContextFnT /*context_fn*/) const
-      -> DiagnosticLocation override {
+struct FakeDiagnosticConverter : DiagnosticConverter<DiagnosticLoc> {
+  auto ConvertLoc(DiagnosticLoc loc, ContextFnT /*context_fn*/) const
+      -> DiagnosticLoc override {
     return loc;
   }
 };
@@ -30,7 +30,7 @@ TEST(SortedDiagnosticEmitterTest, SortErrors) {
   FakeDiagnosticConverter converter;
   Testing::MockDiagnosticConsumer consumer;
   SortingDiagnosticConsumer sorting_consumer(consumer);
-  DiagnosticEmitter<DiagnosticLocation> emitter(converter, sorting_consumer);
+  DiagnosticEmitter<DiagnosticLoc> emitter(converter, sorting_consumer);
 
   emitter.Emit({"f", "line", 2, 1}, TestDiagnostic, "M1");
   emitter.Emit({"f", "line", 1, 1}, TestDiagnostic, "M2");
diff --git a/toolchain/lex/lex.cpp b/toolchain/lex/lex.cpp
index bdd23fbc79a8..048961bd2829 100644
--- a/toolchain/lex/lex.cpp
+++ b/toolchain/lex/lex.cpp
@@ -1270,8 +1270,7 @@ class Lexer::ErrorRecoveryBuffer {
     // Find the end of the token before the target token, and add the new token
     // there. Note that new_token_column is a 1-based column number.
     auto insert_after = TokenIndex(insert_before.index - 1);
-    auto [new_token_line, new_token_column] =
-        buffer_.GetEndLocation(insert_after);
+    auto [new_token_line, new_token_column] = buffer_.GetEndLoc(insert_after);
     new_tokens_.push_back(
         {insert_before,
          {.kind = kind,
diff --git a/toolchain/lex/test_helpers.h b/toolchain/lex/test_helpers.h
index 2510a90ad7bd..b1eae9238d53 100644
--- a/toolchain/lex/test_helpers.h
+++ b/toolchain/lex/test_helpers.h
@@ -24,8 +24,8 @@ class SingleTokenDiagnosticConverter : public DiagnosticConverter<const char*> {
   explicit SingleTokenDiagnosticConverter(llvm::StringRef token)
       : token_(token) {}
 
-  auto ConvertLocation(const char* pos, ContextFnT /*context_fn*/) const
-      -> DiagnosticLocation override {
+  auto ConvertLoc(const char* pos, ContextFnT /*context_fn*/) const
+      -> DiagnosticLoc override {
     CARBON_CHECK(StringRefContainsPointer(token_, pos))
         << "invalid diagnostic location";
     llvm::StringRef prefix = token_.take_front(pos - token_.begin());
diff --git a/toolchain/lex/tokenized_buffer.cpp b/toolchain/lex/tokenized_buffer.cpp
index 65984170d463..680ef4499791 100644
--- a/toolchain/lex/tokenized_buffer.cpp
+++ b/toolchain/lex/tokenized_buffer.cpp
@@ -35,7 +35,7 @@ auto TokenizedBuffer::GetColumnNumber(TokenIndex token) const -> int {
   return GetTokenInfo(token).column + 1;
 }
 
-auto TokenizedBuffer::GetEndLocation(TokenIndex token) const
+auto TokenizedBuffer::GetEndLoc(TokenIndex token) const
     -> std::pair<LineIndex, int> {
   auto line = GetLine(token);
   int column = GetColumnNumber(token);
@@ -345,8 +345,8 @@ auto TokenIterator::Print(llvm::raw_ostream& output) const -> void {
   output << token_.index;
 }
 
-auto TokenizedBuffer::SourceBufferDiagnosticConverter::ConvertLocation(
-    const char* loc, ContextFnT /*context_fn*/) const -> DiagnosticLocation {
+auto TokenizedBuffer::SourceBufferDiagnosticConverter::ConvertLoc(
+    const char* loc, ContextFnT /*context_fn*/) const -> DiagnosticLoc {
   CARBON_CHECK(StringRefContainsPointer(buffer_->source_->text(), loc))
       << "location not within buffer";
   int64_t offset = loc - buffer_->source_->text().begin();
@@ -390,9 +390,9 @@ auto TokenizedBuffer::SourceBufferDiagnosticConverter::ConvertLocation(
           .column_number = column_number + 1};
 }
 
-auto TokenDiagnosticConverter::ConvertLocation(TokenIndex token,
-                                               ContextFnT context_fn) const
-    -> DiagnosticLocation {
+auto TokenDiagnosticConverter::ConvertLoc(TokenIndex token,
+                                          ContextFnT context_fn) const
+    -> DiagnosticLoc {
   // Map the token location into a position within the source buffer.
   const auto& token_info = buffer_->GetTokenInfo(token);
   const auto& line_info = buffer_->GetLineInfo(token_info.token_line);
@@ -402,8 +402,8 @@ auto TokenDiagnosticConverter::ConvertLocation(TokenIndex token,
   // Find the corresponding file location.
   // TODO: Should we somehow indicate in the diagnostic location if this token
   // is a recovery token that doesn't correspond to the original source?
-  DiagnosticLocation loc =
-      TokenizedBuffer::SourceBufferDiagnosticConverter(buffer_).ConvertLocation(
+  DiagnosticLoc loc =
+      TokenizedBuffer::SourceBufferDiagnosticConverter(buffer_).ConvertLoc(
           token_start, context_fn);
   loc.length = buffer_->GetTokenText(token).size();
   return loc;
diff --git a/toolchain/lex/tokenized_buffer.h b/toolchain/lex/tokenized_buffer.h
index af30bc8d39f5..9d92748ec07d 100644
--- a/toolchain/lex/tokenized_buffer.h
+++ b/toolchain/lex/tokenized_buffer.h
@@ -119,8 +119,8 @@ class TokenDiagnosticConverter : public DiagnosticConverter<TokenIndex> {
       : buffer_(buffer) {}
 
   // Map the given token into a diagnostic location.
-  auto ConvertLocation(TokenIndex token, ContextFnT context_fn) const
-      -> DiagnosticLocation override;
+  auto ConvertLoc(TokenIndex token, ContextFnT context_fn) const
+      -> DiagnosticLoc override;
 
  private:
   const TokenizedBuffer* buffer_;
@@ -147,7 +147,7 @@ class TokenizedBuffer : public Printable<TokenizedBuffer> {
 
   // Returns the line and 1-based column number of the first character after
   // this token.
-  auto GetEndLocation(TokenIndex token) const -> std::pair<LineIndex, int>;
+  auto GetEndLoc(TokenIndex token) const -> std::pair<LineIndex, int>;
 
   // Returns the source text lexed into this token.
   auto GetTokenText(TokenIndex token) const -> llvm::StringRef;
@@ -256,8 +256,8 @@ class TokenizedBuffer : public Printable<TokenizedBuffer> {
 
     // Map the given position within the source buffer into a diagnostic
     // location.
-    auto ConvertLocation(const char* loc, ContextFnT context_fn) const
-        -> DiagnosticLocation override;
+    auto ConvertLoc(const char* loc, ContextFnT context_fn) const
+        -> DiagnosticLoc override;
 
    private:
     const TokenizedBuffer* buffer_;
diff --git a/toolchain/parse/context.cpp b/toolchain/parse/context.cpp
index 9dc7f8330f5e..70904296dc90 100644
--- a/toolchain/parse/context.cpp
+++ b/toolchain/parse/context.cpp
@@ -17,7 +17,7 @@
 namespace Carbon::Parse {
 
 // A relative location for characters in errors.
-enum class RelativeLocation : int8_t {
+enum class RelativeLoc : int8_t {
   Around,
   After,
   Before,
@@ -25,20 +25,20 @@ enum class RelativeLocation : int8_t {
 
 }  // namespace Carbon::Parse
 
-// Adapts RelativeLocation for use with formatv.
+// Adapts RelativeLoc for use with formatv.
 template <>
-struct llvm::format_provider<Carbon::Parse::RelativeLocation> {
-  using RelativeLocation = Carbon::Parse::RelativeLocation;
-  static void format(const RelativeLocation& loc, raw_ostream& out,
+struct llvm::format_provider<Carbon::Parse::RelativeLoc> {
+  using RelativeLoc = Carbon::Parse::RelativeLoc;
+  static void format(const RelativeLoc& loc, raw_ostream& out,
                      StringRef /*style*/) {
     switch (loc) {
-      case RelativeLocation::Around:
+      case RelativeLoc::Around:
         out << "around";
         break;
-      case RelativeLocation::After:
+      case RelativeLoc::After:
         out << "after";
         break;
-      case RelativeLocation::Before:
+      case RelativeLoc::Before:
         out << "before";
         break;
     }
@@ -338,14 +338,13 @@ auto Context::DiagnoseOperatorFixity(OperatorFixity fixity) -> void {
     // Infix operators must satisfy the infix operator rules.
     if (!IsLexicallyValidInfixOperator()) {
       CARBON_DIAGNOSTIC(BinaryOperatorRequiresWhitespace, Error,
-                        "Whitespace missing {0} binary operator.",
-                        RelativeLocation);
+                        "Whitespace missing {0} binary operator.", RelativeLoc);
       emitter_->Emit(*position_, BinaryOperatorRequiresWhitespace,
                      tokens().HasLeadingWhitespace(*position_)
-                         ? RelativeLocation::After
+                         ? RelativeLoc::After
                          : (tokens().HasTrailingWhitespace(*position_)
-                                ? RelativeLocation::Before
-                                : RelativeLocation::Around));
+                                ? RelativeLoc::Before
+                                : RelativeLoc::Around));
     }
   } else {
     bool prefix = fixity == OperatorFixity::Prefix;
@@ -356,18 +355,16 @@ auto Context::DiagnoseOperatorFixity(OperatorFixity fixity) -> void {
                 : tokens().HasLeadingWhitespace(*position_))) {
       CARBON_DIAGNOSTIC(UnaryOperatorHasWhitespace, Error,
                         "Whitespace is not allowed {0} this unary operator.",
-                        RelativeLocation);
-      emitter_->Emit(
-          *position_, UnaryOperatorHasWhitespace,
-          prefix ? RelativeLocation::After : RelativeLocation::Before);
+                        RelativeLoc);
+      emitter_->Emit(*position_, UnaryOperatorHasWhitespace,
+                     prefix ? RelativeLoc::After : RelativeLoc::Before);
     } else if (IsLexicallyValidInfixOperator()) {
       // Pre/postfix operators must not satisfy the infix operator rules.
       CARBON_DIAGNOSTIC(UnaryOperatorRequiresWhitespace, Error,
                         "Whitespace is required {0} this unary operator.",
-                        RelativeLocation);
-      emitter_->Emit(
-          *position_, UnaryOperatorRequiresWhitespace,
-          prefix ? RelativeLocation::Before : RelativeLocation::After);
+                        RelativeLoc);
+      emitter_->Emit(*position_, UnaryOperatorRequiresWhitespace,
+                     prefix ? RelativeLoc::Before : RelativeLoc::After);
     }
   }
 }
diff --git a/toolchain/parse/handle_decl_name_and_params.cpp b/toolchain/parse/handle_decl_name_and_params.cpp
index 5259c5c8edcc..eff93583bb93 100644
--- a/toolchain/parse/handle_decl_name_and_params.cpp
+++ b/toolchain/parse/handle_decl_name_and_params.cpp
@@ -25,13 +25,13 @@ static auto HandleDeclNameAndParams(Context& context, State after_name)
     CARBON_DIAGNOSTIC(ExpectedDeclName, Error,
                       "`{0}` introducer should be followed by a name.",
                       Lex::TokenKind);
-    Lex::TokenIndex location = *context.position();
-    if (context.tokens().GetKind(location) == Lex::TokenKind::FileEnd) {
-      // The end of file is often an especially unhelpful location. If that's
-      // the best we can do here, back up the location to the introducer itself.
-      location = state.token;
+    Lex::TokenIndex token = *context.position();
+    if (context.tokens().GetKind(token) == Lex::TokenKind::FileEnd) {
+      // The end of file is an unhelpful diagnostic location. Instead, use the
+      // introducer token.
+      token = state.token;
     }
-    context.emitter().Emit(location, ExpectedDeclName,
+    context.emitter().Emit(token, ExpectedDeclName,
                            context.tokens().GetKind(state.token));
     context.ReturnErrorOnState();
     context.AddLeafNode(NodeKind::InvalidParse, *context.position(),
diff --git a/toolchain/parse/tree_node_diagnostic_converter.h b/toolchain/parse/tree_node_diagnostic_converter.h
index 87f7c75393de..c5ad601cf1d7 100644
--- a/toolchain/parse/tree_node_diagnostic_converter.h
+++ b/toolchain/parse/tree_node_diagnostic_converter.h
@@ -11,16 +11,16 @@
 
 namespace Carbon::Parse {
 
-class NodeLocation {
+class NodeLoc {
  public:
   // NOLINTNEXTLINE(google-explicit-constructor)
-  NodeLocation(NodeId node_id) : NodeLocation(node_id, false) {}
-  NodeLocation(NodeId node_id, bool token_only)
+  NodeLoc(NodeId node_id) : NodeLoc(node_id, false) {}
+  NodeLoc(NodeId node_id, bool token_only)
       : node_id_(node_id), token_only_(token_only) {}
   // TODO: Have some other way of representing diagnostic that applies to a file
   // as a whole.
   // NOLINTNEXTLINE(google-explicit-constructor)
-  NodeLocation(InvalidNodeId node_id) : NodeLocation(node_id, false) {}
+  NodeLoc(InvalidNodeId node_id) : NodeLoc(node_id, false) {}
 
   auto node_id() const -> NodeId { return node_id_; }
   auto token_only() const -> bool { return token_only_; }
@@ -30,35 +30,33 @@ class NodeLocation {
   bool token_only_;
 };
 
-class NodeLocationConverter : public DiagnosticConverter<NodeLocation> {
+class NodeLocConverter : public DiagnosticConverter<NodeLoc> {
  public:
-  explicit NodeLocationConverter(const Lex::TokenizedBuffer* tokens,
-                                 llvm::StringRef filename,
-                                 const Tree* parse_tree)
+  explicit NodeLocConverter(const Lex::TokenizedBuffer* tokens,
+                            llvm::StringRef filename, const Tree* parse_tree)
       : token_converter_(tokens),
         filename_(filename),
         parse_tree_(parse_tree) {}
 
   // Map the given token into a diagnostic location.
-  auto ConvertLocation(NodeLocation node_location, ContextFnT context_fn) const
-      -> DiagnosticLocation override {
+  auto ConvertLoc(NodeLoc node_loc, ContextFnT context_fn) const
+      -> DiagnosticLoc override {
     // Support the invalid token as a way to emit only the filename, when there
     // is no line association.
-    if (!node_location.node_id().is_valid()) {
+    if (!node_loc.node_id().is_valid()) {
       return {.filename = filename_};
     }
 
-    if (node_location.token_only()) {
-      return token_converter_.ConvertLocation(
-          parse_tree_->node_token(node_location.node_id()), context_fn);
+    if (node_loc.token_only()) {
+      return token_converter_.ConvertLoc(
+          parse_tree_->node_token(node_loc.node_id()), context_fn);
     }
 
     // Construct a location that encompasses all tokens that descend from this
     // node (including the root).
-    Lex::TokenIndex start_token =
-        parse_tree_->node_token(node_location.node_id());
+    Lex::TokenIndex start_token = parse_tree_->node_token(node_loc.node_id());
     Lex::TokenIndex end_token = start_token;
-    for (NodeId desc : parse_tree_->postorder(node_location.node_id())) {
+    for (NodeId desc : parse_tree_->postorder(node_loc.node_id())) {
       Lex::TokenIndex desc_token = parse_tree_->node_token(desc);
       if (!desc_token.is_valid()) {
         continue;
@@ -69,13 +67,12 @@ class NodeLocationConverter : public DiagnosticConverter<NodeLocation> {
         end_token = desc_token;
       }
     }
-    DiagnosticLocation start_loc =
-        token_converter_.ConvertLocation(start_token, context_fn);
+    DiagnosticLoc start_loc =
+        token_converter_.ConvertLoc(start_token, context_fn);
     if (start_token == end_token) {
       return start_loc;
     }
-    DiagnosticLocation end_loc =
-        token_converter_.ConvertLocation(end_token, context_fn);
+    DiagnosticLoc end_loc = token_converter_.ConvertLoc(end_token, context_fn);
     // For multiline locations we simply return the rest of the line for now
     // since true multiline locations are not yet supported.
     if (start_loc.line_number != end_loc.line_number) {
diff --git a/toolchain/sem_ir/constant.cpp b/toolchain/sem_ir/constant.cpp
index 4ddf89da22f1..410c3ce76190 100644
--- a/toolchain/sem_ir/constant.cpp
+++ b/toolchain/sem_ir/constant.cpp
@@ -26,7 +26,7 @@ auto ConstantStore::GetOrAdd(Inst inst, bool is_symbolic) -> ConstantId {
 
   // Create the new inst and insert the new node.
   auto inst_id = constants_.getContext()->insts().AddInNoBlock(
-      LocationIdAndInst::Untyped(Parse::NodeId::Invalid, inst));
+      LocIdAndInst::Untyped(Parse::NodeId::Invalid, inst));
   auto constant_id = is_symbolic
                          ? SemIR::ConstantId::ForSymbolicConstant(inst_id)
                          : SemIR::ConstantId::ForTemplateConstant(inst_id);
diff --git a/toolchain/sem_ir/file.h b/toolchain/sem_ir/file.h
index a1da8130a96b..d8255f1f89f9 100644
--- a/toolchain/sem_ir/file.h
+++ b/toolchain/sem_ir/file.h
@@ -223,7 +223,7 @@ class File : public Printable<File> {
   // for references of builtins).
   ValueStore<ImportIRId> import_irs_;
 
-  // Related IR instructions. These are created for LocationIds for instructions
+  // Related IR instructions. These are created for LocIds for instructions
   // that are import-related.
   ValueStore<ImportIRInstId> import_ir_insts_;
 
diff --git a/toolchain/sem_ir/formatter.cpp b/toolchain/sem_ir/formatter.cpp
index 1836e5538508..8404ac14cb7f 100644
--- a/toolchain/sem_ir/formatter.cpp
+++ b/toolchain/sem_ir/formatter.cpp
@@ -83,8 +83,7 @@ class InstNamer {
         insts[fn.return_slot_id.index] = {
             fn_scope,
             GetScopeInfo(fn_scope).insts.AllocateName(
-                *this, sem_ir.insts().GetLocationId(fn.return_slot_id),
-                "return")};
+                *this, sem_ir.insts().GetLocId(fn.return_slot_id), "return")};
       }
       if (!fn.body_block_ids.empty()) {
         AddBlockLabel(fn_scope, fn.body_block_ids.front(), "entry", fn_loc);
@@ -269,7 +268,7 @@ class InstNamer {
       return Name(allocated.insert({name, NameResult()}).first);
     }
 
-    auto AllocateName(const InstNamer& namer, SemIR::LocationId loc_id,
+    auto AllocateName(const InstNamer& namer, SemIR::LocId loc_id,
                       std::string name) -> Name {
       // The best (shortest) name for this instruction so far, and the current
       // name for it.
@@ -346,8 +345,7 @@ class InstNamer {
 
   auto AddBlockLabel(ScopeId scope_id, InstBlockId block_id,
                      std::string name = "",
-                     SemIR::LocationId loc_id = SemIR::LocationId::Invalid)
-      -> void {
+                     SemIR::LocId loc_id = SemIR::LocId::Invalid) -> void {
     if (!block_id.is_valid() || labels[block_id.index].second) {
       return;
     }
@@ -355,7 +353,7 @@ class InstNamer {
     if (!loc_id.is_valid()) {
       if (const auto& block = sem_ir_.inst_blocks().Get(block_id);
           !block.empty()) {
-        loc_id = sem_ir_.insts().GetLocationId(block.front());
+        loc_id = sem_ir_.insts().GetLocId(block.front());
       }
     }
 
@@ -366,8 +364,8 @@ class InstNamer {
 
   // Finds and adds a suitable block label for the given SemIR instruction that
   // represents some kind of branch.
-  auto AddBlockLabel(ScopeId scope_id, SemIR::LocationId loc_id,
-                     AnyBranch branch) -> void {
+  auto AddBlockLabel(ScopeId scope_id, SemIR::LocId loc_id, AnyBranch branch)
+      -> void {
     llvm::StringRef name;
     switch (parse_tree_.node_kind(loc_id.node_id())) {
       case Parse::NodeKind::IfExprIf:
@@ -454,7 +452,7 @@ class InstNamer {
       auto add_inst_name = [&](std::string name) {
         insts[inst_id.index] = {
             scope_id, scope.insts.AllocateName(
-                          *this, sem_ir_.insts().GetLocationId(inst_id), name)};
+                          *this, sem_ir_.insts().GetLocId(inst_id), name)};
       };
       auto add_inst_name_id = [&](NameId name_id, llvm::StringRef suffix = "") {
         add_inst_name(
@@ -462,8 +460,7 @@ class InstNamer {
       };
 
       if (auto branch = untyped_inst.TryAs<AnyBranch>()) {
-        AddBlockLabel(scope_id, sem_ir_.insts().GetLocationId(inst_id),
-                      *branch);
+        AddBlockLabel(scope_id, sem_ir_.insts().GetLocId(inst_id), *branch);
       }
 
       CARBON_KIND_SWITCH(untyped_inst) {
diff --git a/toolchain/sem_ir/ids.h b/toolchain/sem_ir/ids.h
index 79ce0f1a9fd5..d2cb2ceaacb4 100644
--- a/toolchain/sem_ir/ids.h
+++ b/toolchain/sem_ir/ids.h
@@ -496,21 +496,20 @@ struct ImportIRInstId : public IdBase, public Printable<InstId> {
 // - index > Invalid: A Parse::NodeId in the current IR.
 // - index < Invalid: An ImportIRInstId.
 // - index == Invalid: Can be used for either.
-struct LocationId : public IdBase, public Printable<FunctionId> {
+struct LocId : public IdBase, public Printable<FunctionId> {
   // An explicitly invalid function ID.
-  static const LocationId Invalid;
+  static const LocId Invalid;
 
   // NOLINTNEXTLINE(google-explicit-constructor)
-  constexpr LocationId(Parse::InvalidNodeId /*invalid*/)
-      : IdBase(InvalidIndex) {}
+  constexpr LocId(Parse::InvalidNodeId /*invalid*/) : IdBase(InvalidIndex) {}
 
   // NOLINTNEXTLINE(google-explicit-constructor)
-  constexpr LocationId(Parse::NodeId node_id) : IdBase(node_id.index) {
+  constexpr LocId(Parse::NodeId node_id) : IdBase(node_id.index) {
     CARBON_CHECK(node_id.is_valid() == is_valid());
   }
 
   // NOLINTNEXTLINE(google-explicit-constructor)
-  constexpr LocationId(ImportIRInstId inst_id)
+  constexpr LocId(ImportIRInstId inst_id)
       : IdBase(InvalidIndex + ImportIRInstId::InvalidIndex - inst_id.index) {
     CARBON_CHECK(inst_id.is_valid() == is_valid());
   }
@@ -542,7 +541,7 @@ struct LocationId : public IdBase, public Printable<FunctionId> {
   }
 };
 
-constexpr LocationId LocationId::Invalid = LocationId(Parse::NodeId::Invalid);
+constexpr LocId LocId::Invalid = LocId(Parse::NodeId::Invalid);
 
 }  // namespace Carbon::SemIR
 
diff --git a/toolchain/sem_ir/import_ir.h b/toolchain/sem_ir/import_ir.h
index dd36107f45f8..97cce05ef6e6 100644
--- a/toolchain/sem_ir/import_ir.h
+++ b/toolchain/sem_ir/import_ir.h
@@ -22,7 +22,7 @@ struct ImportIR : public Printable<ImportIR> {
 };
 
 // A reference to an instruction in an imported IR. Used for diagnostics with
-// LocationId.
+// LocId.
 struct ImportIRInst : public Printable<ImportIRInst> {
   auto Print(llvm::raw_ostream& out) const -> void {
     out << ir_id << ":" << inst_id;
diff --git a/toolchain/sem_ir/inst.h b/toolchain/sem_ir/inst.h
index dcb13b5cfbac..c311d696efd0 100644
--- a/toolchain/sem_ir/inst.h
+++ b/toolchain/sem_ir/inst.h
@@ -288,15 +288,15 @@ inline auto operator<<(llvm::raw_ostream& out, TypedInst inst)
   return out;
 }
 
-// Associates a LocationId and Inst in order to provide type-checking that the
+// Associates a LocId and Inst in order to provide type-checking that the
 // TypedNodeId corresponds to the InstT.
-struct LocationIdAndInst {
+struct LocIdAndInst {
   // In cases where the NodeId is untyped, an inst_id, or the InstT is unknown,
   // the NodeId check can't be done at compile time.
   // TODO: Consider runtime validation that InstT::Kind::TypedNodeId
   // corresponds.
-  static auto Untyped(LocationId loc_id, Inst inst) -> LocationIdAndInst {
-    return LocationIdAndInst(loc_id, inst, /*is_untyped=*/true);
+  static auto Untyped(LocId loc_id, Inst inst) -> LocIdAndInst {
+    return LocIdAndInst(loc_id, inst, /*is_untyped=*/true);
   }
 
   // For the common case, support construction as:
@@ -304,7 +304,7 @@ struct LocationIdAndInst {
   template <typename InstT>
     requires(Internal::HasNodeId<InstT>)
   // NOLINTNEXTLINE(google-explicit-constructor)
-  LocationIdAndInst(decltype(InstT::Kind)::TypedNodeId node_id, InstT inst)
+  LocIdAndInst(decltype(InstT::Kind)::TypedNodeId node_id, InstT inst)
       : loc_id(node_id), inst(inst) {}
 
   // For cases with no parse node, support construction as:
@@ -312,23 +312,22 @@ struct LocationIdAndInst {
   template <typename InstT>
     requires(!Internal::HasNodeId<InstT>)
   // NOLINTNEXTLINE(google-explicit-constructor)
-  LocationIdAndInst(InstT inst) : loc_id(Parse::NodeId::Invalid), inst(inst) {}
+  LocIdAndInst(InstT inst) : loc_id(Parse::NodeId::Invalid), inst(inst) {}
 
-  // If TypedNodeId is Parse::NodeId, allow construction with a LocationId
+  // If TypedNodeId is Parse::NodeId, allow construction with a LocId
   // rather than requiring Untyped.
   // TODO: This is somewhat historical due to fetching the NodeId from insts()
   // for things like Temporary; should we require Untyped in these cases?
   template <typename InstT>
     requires(std::same_as<typename decltype(InstT::Kind)::TypedNodeId,
                           Parse::NodeId>)
-  LocationIdAndInst(LocationId loc_id, InstT inst)
-      : loc_id(loc_id), inst(inst) {}
+  LocIdAndInst(LocId loc_id, InstT inst) : loc_id(loc_id), inst(inst) {}
 
-  LocationId loc_id;
+  LocId loc_id;
   Inst inst;
 
  private:
-  explicit LocationIdAndInst(LocationId loc_id, Inst inst, bool /*is_untyped*/)
+  explicit LocIdAndInst(LocId loc_id, Inst inst, bool /*is_untyped*/)
       : loc_id(loc_id), inst(inst) {}
 };
 
@@ -340,7 +339,7 @@ class InstStore {
   // instruction block. Check::Context::AddInst or InstBlockStack::AddInst
   // should usually be used instead, to add the instruction to the current
   // block.
-  auto AddInNoBlock(LocationIdAndInst loc_id_and_inst) -> InstId {
+  auto AddInNoBlock(LocIdAndInst loc_id_and_inst) -> InstId {
     loc_ids_.push_back(loc_id_and_inst.loc_id);
     return values_.Add(loc_id_and_inst.inst);
   }
@@ -349,8 +348,8 @@ class InstStore {
   auto Get(InstId inst_id) const -> Inst { return values_.Get(inst_id); }
 
   // Returns the requested instruction and its location ID.
-  auto GetWithLocationId(InstId inst_id) const -> LocationIdAndInst {
-    return LocationIdAndInst::Untyped(GetLocationId(inst_id), Get(inst_id));
+  auto GetWithLocId(InstId inst_id) const -> LocIdAndInst {
+    return LocIdAndInst::Untyped(GetLocId(inst_id), Get(inst_id));
   }
 
   // Returns whether the requested instruction is the specified type.
@@ -383,7 +382,7 @@ class InstStore {
     return TryGetAs<InstT>(inst_id);
   }
 
-  auto GetLocationId(InstId inst_id) const -> LocationId {
+  auto GetLocId(InstId inst_id) const -> LocId {
     CARBON_CHECK(inst_id.index >= 0) << inst_id.index;
     CARBON_CHECK(inst_id.index < (int)loc_ids_.size())
         << inst_id.index << " " << loc_ids_.size();
@@ -394,15 +393,14 @@ class InstStore {
   auto Set(InstId inst_id, Inst inst) -> void { values_.Get(inst_id) = inst; }
 
   // Overwrites a given instruction's location with a new value.
-  auto SetLocationId(InstId inst_id, LocationId loc_id) -> void {
+  auto SetLocId(InstId inst_id, LocId loc_id) -> void {
     loc_ids_[inst_id.index] = loc_id;
   }
 
   // Overwrites a given instruction and location ID with a new value.
-  auto SetLocationIdAndInst(InstId inst_id, LocationIdAndInst loc_id_and_inst)
-      -> void {
+  auto SetLocIdAndInst(InstId inst_id, LocIdAndInst loc_id_and_inst) -> void {
     Set(inst_id, loc_id_and_inst.inst);
-    SetLocationId(inst_id, loc_id_and_inst.loc_id);
+    SetLocId(inst_id, loc_id_and_inst.loc_id);
   }
 
   // Reserves space.
@@ -415,7 +413,7 @@ class InstStore {
   auto size() const -> int { return values_.size(); }
 
  private:
-  llvm::SmallVector<LocationId> loc_ids_;
+  llvm::SmallVector<LocId> loc_ids_;
   ValueStore<InstId> values_;
 };
 
diff --git a/toolchain/source/source_buffer.cpp b/toolchain/source/source_buffer.cpp
index 09248e2be823..ee340385bc4a 100644
--- a/toolchain/source/source_buffer.cpp
+++ b/toolchain/source/source_buffer.cpp
@@ -12,9 +12,8 @@ namespace Carbon {
 
 namespace {
 struct FilenameConverter : DiagnosticConverter<llvm::StringRef> {
-  auto ConvertLocation(llvm::StringRef filename,
-                       ContextFnT /*context_fn*/) const
-      -> DiagnosticLocation override {
+  auto ConvertLoc(llvm::StringRef filename, ContextFnT /*context_fn*/) const
+      -> DiagnosticLoc override {
     return {.filename = filename};
   }
 };