diff --git a/CodeGeneration/Sources/SyntaxSupport/AttributeNodes.swift b/CodeGeneration/Sources/SyntaxSupport/AttributeNodes.swift
index da02d28f5a2..e65212950e4 100644
--- a/CodeGeneration/Sources/SyntaxSupport/AttributeNodes.swift
+++ b/CodeGeneration/Sources/SyntaxSupport/AttributeNodes.swift
@@ -184,6 +184,7 @@ public let ATTRIBUTE_NODES: [Node] = [
     base: .syntax,
     nameForDiagnostics: "version",
     documentation: "A single platform/version pair in an attribute, e.g. `iOS 10.1`.",
+    traits: ["WithTrailingComma"],
     children: [
       Child(
         name: "AvailabilityVersionRestriction",
diff --git a/CodeGeneration/Sources/SyntaxSupport/AvailabilityNodes.swift b/CodeGeneration/Sources/SyntaxSupport/AvailabilityNodes.swift
index ca87c268c81..b619a4bfaa7 100644
--- a/CodeGeneration/Sources/SyntaxSupport/AvailabilityNodes.swift
+++ b/CodeGeneration/Sources/SyntaxSupport/AvailabilityNodes.swift
@@ -21,6 +21,7 @@ public let AVAILABILITY_NODES: [Node] = [
     base: .syntax,
     nameForDiagnostics: "availability argument",
     documentation: "A single argument to an `@available` argument like `*`, `iOS 10.1`, or `message: \"This has been deprecated\"`.",
+    traits: ["WithTrailingComma"],
     children: [
       Child(
         name: "Entry",
diff --git a/CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift b/CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift
index b2d1eafd1f2..e10c6f228f5 100644
--- a/CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift
+++ b/CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift
@@ -1871,6 +1871,7 @@ public let DECL_NODES: [Node] = [
     kind: .precedenceGroupNameElement,
     base: .syntax,
     nameForDiagnostics: nil,
+    traits: ["WithTrailingComma"],
     children: [
       Child(
         name: "Name",
@@ -2268,6 +2269,7 @@ public let DECL_NODES: [Node] = [
     traits: [
       "IdentifiedDecl",
       "WithAttributes",
+      "WithModifiers",
     ],
     children: [
       Child(
diff --git a/Sources/SwiftSyntax/generated/SyntaxTraits.swift b/Sources/SwiftSyntax/generated/SyntaxTraits.swift
index 58edd5e125d..67c392ba645 100644
--- a/Sources/SwiftSyntax/generated/SyntaxTraits.swift
+++ b/Sources/SwiftSyntax/generated/SyntaxTraits.swift
@@ -499,6 +499,10 @@ extension AssociatedtypeDeclSyntax: IdentifiedDeclSyntax, WithAttributesSyntax,
 
 extension AttributedTypeSyntax: WithAttributesSyntax {}
 
+extension AvailabilityArgumentSyntax: WithTrailingCommaSyntax {}
+
+extension AvailabilityVersionRestrictionListEntrySyntax: WithTrailingCommaSyntax {}
+
 extension CaseItemSyntax: WithTrailingCommaSyntax {}
 
 extension CatchClauseSyntax: WithCodeBlockSyntax {}
@@ -603,6 +607,8 @@ extension PoundSourceLocationSyntax: ParenthesizedSyntax {}
 
 extension PrecedenceGroupDeclSyntax: IdentifiedDeclSyntax, WithAttributesSyntax, WithModifiersSyntax {}
 
+extension PrecedenceGroupNameElementSyntax: WithTrailingCommaSyntax {}
+
 extension PrimaryAssociatedTypeSyntax: WithTrailingCommaSyntax {}
 
 extension ProtocolDeclSyntax: DeclGroupSyntax, IdentifiedDeclSyntax, WithAttributesSyntax, WithModifiersSyntax {}
@@ -635,7 +641,7 @@ extension TupleTypeSyntax: ParenthesizedSyntax {}
 
 extension TypeEffectSpecifiersSyntax: EffectSpecifiersSyntax {}
 
-extension TypealiasDeclSyntax: IdentifiedDeclSyntax, WithAttributesSyntax {}
+extension TypealiasDeclSyntax: IdentifiedDeclSyntax, WithAttributesSyntax, WithModifiersSyntax {}
 
 extension VariableDeclSyntax: WithAttributesSyntax, WithModifiersSyntax {}
 
diff --git a/Sources/SwiftSyntaxBuilder/generated/ResultBuilders.swift b/Sources/SwiftSyntaxBuilder/generated/ResultBuilders.swift
index 05f154af2af..4d5ec8f1a2c 100644
--- a/Sources/SwiftSyntaxBuilder/generated/ResultBuilders.swift
+++ b/Sources/SwiftSyntaxBuilder/generated/ResultBuilders.swift
@@ -339,7 +339,10 @@ public struct AvailabilitySpecListBuilder {
   /// If declared, this will be called on the partial result from the outermost
   /// block statement to produce the final returned result.
   public static func buildFinalResult(_ component: Component) -> FinalResult {
-    return .init(component)
+    let lastIndex = component.count - 1
+    return .init(component.enumerated().map { index, source in
+      return index < lastIndex ? source.ensuringTrailingComma() : source
+      })
   }
 }
 
@@ -419,7 +422,10 @@ public struct AvailabilityVersionRestrictionListBuilder {
   /// If declared, this will be called on the partial result from the outermost
   /// block statement to produce the final returned result.
   public static func buildFinalResult(_ component: Component) -> FinalResult {
-    return .init(component)
+    let lastIndex = component.count - 1
+    return .init(component.enumerated().map { index, source in
+      return index < lastIndex ? source.ensuringTrailingComma() : source
+      })
   }
 }
 
@@ -3128,7 +3134,10 @@ public struct PrecedenceGroupNameListBuilder {
   /// If declared, this will be called on the partial result from the outermost
   /// block statement to produce the final returned result.
   public static func buildFinalResult(_ component: Component) -> FinalResult {
-    return .init(component)
+    let lastIndex = component.count - 1
+    return .init(component.enumerated().map { index, source in
+      return index < lastIndex ? source.ensuringTrailingComma() : source
+      })
   }
 }
 
diff --git a/Tests/SwiftSyntaxMacrosTest/MacroSystemTests.swift b/Tests/SwiftSyntaxMacrosTest/MacroSystemTests.swift
index 58f43e2fec9..8306e73332f 100644
--- a/Tests/SwiftSyntaxMacrosTest/MacroSystemTests.swift
+++ b/Tests/SwiftSyntaxMacrosTest/MacroSystemTests.swift
@@ -1112,7 +1112,7 @@ final class MacroSystemTests: XCTestCase {
       expandedSource: #"""
         struct S {
           @attr static var value1 = 1
-          @attr typealias A = B
+          @attr static typealias A = B
         }
         """#,
       macros: ["decls": DeclsFromStringsMacro.self],