diff --git a/ql/ql/src/codeql/Locations.qll b/ql/ql/src/codeql/Locations.qll
index ae8058c916df..e03c84f98fa5 100644
--- a/ql/ql/src/codeql/Locations.qll
+++ b/ql/ql/src/codeql/Locations.qll
@@ -1,4 +1,6 @@
 /** Provides classes for working with locations. */
+overlay[local]
+module;
 
 import files.FileSystem
 
diff --git a/ql/ql/src/codeql/files/FileSystem.qll b/ql/ql/src/codeql/files/FileSystem.qll
index 5a219f3b7f0c..52174250af0c 100644
--- a/ql/ql/src/codeql/files/FileSystem.qll
+++ b/ql/ql/src/codeql/files/FileSystem.qll
@@ -1,4 +1,6 @@
 /** Provides classes for working with files and folders. */
+overlay[local?]
+module;
 
 private import codeql_ql.ast.internal.TreeSitter
 private import codeql.Locations
diff --git a/ql/ql/src/codeql_ql/StructuredLogs.qll b/ql/ql/src/codeql_ql/StructuredLogs.qll
index 4c0ef69fd554..87527eae1d23 100644
--- a/ql/ql/src/codeql_ql/StructuredLogs.qll
+++ b/ql/ql/src/codeql_ql/StructuredLogs.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import ql
 private import codeql_ql.ast.internal.TreeSitter
 private import experimental.RA
@@ -23,6 +26,7 @@ private float stringToTimestamp(string str) {
 }
 
 bindingset[s]
+overlay[global]
 private Predicate getPredicateFromPosition(string s) {
   exists(string r, string filepath, int startline | r = "(.*):(\\d+),(\\d+)-(\\d+),(\\d+)" |
     filepath = s.regexpCapture(r, 1) and
@@ -397,6 +401,7 @@ module KindPredicatesLog {
 
     string getPosition() { result = this.getString("position") }
 
+    overlay[global]
     Predicate getPredicate() { result = getPredicateFromPosition(this.getPosition()) }
 
     /**
diff --git a/ql/ql/src/codeql_ql/ast/internal/TreeSitter.qll b/ql/ql/src/codeql_ql/ast/internal/TreeSitter.qll
index 2d4a9d654652..c81830e1d59a 100644
--- a/ql/ql/src/codeql_ql/ast/internal/TreeSitter.qll
+++ b/ql/ql/src/codeql_ql/ast/internal/TreeSitter.qll
@@ -23,6 +23,7 @@ private predicate discardLocation(@location_default loc) {
   )
 }
 
+overlay[local]
 module QL {
   /** The base class for all AST nodes */
   class AstNode extends @ql_ast_node {
@@ -67,7 +68,6 @@ module QL {
   }
 
   /** Gets the file containing the given `node`. */
-  overlay[local]
   private @file getNodeFile(@ql_ast_node node) {
     exists(@location_default loc | ql_ast_node_location(node, loc) |
       locations_default(loc, result, _, _, _, _)
@@ -75,7 +75,6 @@ module QL {
   }
 
   /** Holds if `node` is in the `file` and is part of the overlay base database. */
-  overlay[local]
   private predicate discardableAstNode(@file file, @ql_ast_node node) {
     not isOverlay() and file = getNodeFile(node)
   }
@@ -1315,6 +1314,7 @@ module QL {
   }
 }
 
+overlay[local]
 module Dbscheme {
   /** The base class for all AST nodes */
   class AstNode extends @dbscheme_ast_node {
@@ -1359,7 +1359,6 @@ module Dbscheme {
   }
 
   /** Gets the file containing the given `node`. */
-  overlay[local]
   private @file getNodeFile(@dbscheme_ast_node node) {
     exists(@location_default loc | dbscheme_ast_node_location(node, loc) |
       locations_default(loc, result, _, _, _, _)
@@ -1367,7 +1366,6 @@ module Dbscheme {
   }
 
   /** Holds if `node` is in the `file` and is part of the overlay base database. */
-  overlay[local]
   private predicate discardableAstNode(@file file, @dbscheme_ast_node node) {
     not isOverlay() and file = getNodeFile(node)
   }
@@ -1673,6 +1671,7 @@ module Dbscheme {
   }
 }
 
+overlay[local]
 module Blame {
   /** The base class for all AST nodes */
   class AstNode extends @blame_ast_node {
@@ -1717,7 +1716,6 @@ module Blame {
   }
 
   /** Gets the file containing the given `node`. */
-  overlay[local]
   private @file getNodeFile(@blame_ast_node node) {
     exists(@location_default loc | blame_ast_node_location(node, loc) |
       locations_default(loc, result, _, _, _, _)
@@ -1725,7 +1723,6 @@ module Blame {
   }
 
   /** Holds if `node` is in the `file` and is part of the overlay base database. */
-  overlay[local]
   private predicate discardableAstNode(@file file, @blame_ast_node node) {
     not isOverlay() and file = getNodeFile(node)
   }
@@ -1808,6 +1805,7 @@ module Blame {
   }
 }
 
+overlay[local]
 module JSON {
   /** The base class for all AST nodes */
   class AstNode extends @json_ast_node {
@@ -1852,7 +1850,6 @@ module JSON {
   }
 
   /** Gets the file containing the given `node`. */
-  overlay[local]
   private @file getNodeFile(@json_ast_node node) {
     exists(@location_default loc | json_ast_node_location(node, loc) |
       locations_default(loc, result, _, _, _, _)
@@ -1860,7 +1857,6 @@ module JSON {
   }
 
   /** Holds if `node` is in the `file` and is part of the overlay base database. */
-  overlay[local]
   private predicate discardableAstNode(@file file, @json_ast_node node) {
     not isOverlay() and file = getNodeFile(node)
   }
diff --git a/ql/ql/src/experimental/RA.qll b/ql/ql/src/experimental/RA.qll
index 7187ebfc8c74..5eb804555620 100644
--- a/ql/ql/src/experimental/RA.qll
+++ b/ql/ql/src/experimental/RA.qll
@@ -1,6 +1,5 @@
-/**
- * Parses RA expressions.
- */
+overlay[local]
+module;
 
 /**
  * A predicate that contains RA.
diff --git a/ql/ql/src/queries/performance/LargeTupleSum.ql b/ql/ql/src/queries/performance/LargeTupleSum.ql
index e5bbed79bbd3..4e5ca6622e80 100644
--- a/ql/ql/src/queries/performance/LargeTupleSum.ql
+++ b/ql/ql/src/queries/performance/LargeTupleSum.ql
@@ -6,6 +6,7 @@ import ql
 import codeql_ql.StructuredLogs
 import KindPredicatesLog
 
+overlay[local]
 module SumCounts implements Fold<int> {
   int base(PipeLineRun run) { result = sum(int i | | run.getCount(i)) }
 
diff --git a/ql/ql/test/experimental/raparser.ql b/ql/ql/test/experimental/raparser.ql
index 29489e2a968c..5704b0facdb4 100644
--- a/ql/ql/test/experimental/raparser.ql
+++ b/ql/ql/test/experimental/raparser.ql
@@ -1,5 +1,6 @@
 import experimental.RA
 
+overlay[local]
 class TestPredicate extends string {
   TestPredicate() { this = "p1" }
 
diff --git a/ruby/ql/lib/codeql/Locations.qll b/ruby/ql/lib/codeql/Locations.qll
index 148c6b01f2d9..df52d6822a2e 100644
--- a/ruby/ql/lib/codeql/Locations.qll
+++ b/ruby/ql/lib/codeql/Locations.qll
@@ -1,4 +1,6 @@
 /** Provides classes for working with locations. */
+overlay[local]
+module;
 
 import files.FileSystem
 
diff --git a/ruby/ql/lib/codeql/files/FileSystem.qll b/ruby/ql/lib/codeql/files/FileSystem.qll
index 528dde52fd91..6cc771fad9d2 100644
--- a/ruby/ql/lib/codeql/files/FileSystem.qll
+++ b/ruby/ql/lib/codeql/files/FileSystem.qll
@@ -1,4 +1,6 @@
 /** Provides classes for working with files and folders. */
+overlay[local]
+module;
 
 private import codeql.Locations
 private import codeql.util.FileSystem
diff --git a/ruby/ql/lib/codeql/ruby/AST.qll b/ruby/ql/lib/codeql/ruby/AST.qll
index bd42696a8dbe..2c2dbdfa5322 100644
--- a/ruby/ql/lib/codeql/ruby/AST.qll
+++ b/ruby/ql/lib/codeql/ruby/AST.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 import codeql.Locations
 import ast.Call
 import ast.Control
diff --git a/ruby/ql/lib/codeql/ruby/Diagnostics.qll b/ruby/ql/lib/codeql/ruby/Diagnostics.qll
index 58de14b8fcf5..5b55eec38098 100644
--- a/ruby/ql/lib/codeql/ruby/Diagnostics.qll
+++ b/ruby/ql/lib/codeql/ruby/Diagnostics.qll
@@ -1,4 +1,6 @@
 /** Provides classes relating to extraction diagnostics. */
+overlay[local]
+module;
 
 private import codeql.Locations
 
diff --git a/ruby/ql/lib/codeql/ruby/ast/Call.qll b/ruby/ql/lib/codeql/ruby/ast/Call.qll
index 8a69ebd36fbb..ab7a0603b670 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Call.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Call.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.AST
 private import internal.Call
@@ -38,6 +41,7 @@ class Call extends Expr instanceof CallImpl {
    * foo :bar "baz", qux: 123
    * ```
    */
+  overlay[global]
   final Expr getKeywordArgument(string keyword) {
     exists(Pair p |
       p = this.getAnArgument() and
@@ -52,6 +56,7 @@ class Call extends Expr instanceof CallImpl {
   final int getNumberOfArguments() { result = super.getNumberOfArgumentsImpl() }
 
   /** Gets a potential target of this call, if any. */
+  overlay[global]
   final Callable getATarget() {
     exists(DataFlowCall c |
       this = c.asCall().getExpr() and
@@ -153,6 +158,7 @@ class MethodCall extends Call instanceof MethodCallImpl {
  * TODO: When API Graphs is able to resolve calls to methods like `Kernel.send`
  * this class is no longer necessary and should be removed.
  */
+overlay[global]
 class UnknownMethodCall extends MethodCall {
   UnknownMethodCall() { not exists(this.(Call).getATarget()) }
 }
diff --git a/ruby/ql/lib/codeql/ruby/ast/Constant.qll b/ruby/ql/lib/codeql/ruby/ast/Constant.qll
index fef057bc88ee..125aef4980fe 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Constant.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Constant.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.AST
 private import internal.Constant
@@ -6,6 +9,7 @@ private import internal.Variable
 private import internal.TreeSitter
 
 /** A constant value. */
+overlay[global]
 class ConstantValue extends TConstantValue {
   /** Gets a textual representation of this constant value. */
   final string toString() { this.hasValueWithType(result, _) }
@@ -134,6 +138,7 @@ class ConstantValue extends TConstantValue {
 }
 
 /** Provides different sub classes of `ConstantValue`. */
+overlay[global]
 module ConstantValue {
   /** A constant integer value. */
   class ConstantIntegerValue extends ConstantValue, TInt { }
@@ -268,15 +273,18 @@ class ConstantReadAccess extends ConstantAccess {
    *
    * the value being read at `M::CONST` is `"const"`.
    */
+  overlay[global]
   Expr getValue() { result = getConstantReadAccessValue(this) }
 
   /**
    * Gets a fully qualified name for this constant read, based on the context in
    * which it occurs.
    */
+  overlay[global]
   string getAQualifiedName() { result = resolveConstant(this) }
 
   /** Gets the module that this read access resolves to, if any. */
+  overlay[global]
   Module getModule() { result = resolveConstantReadAccess(this) }
 
   final override string getAPrimaryQlClass() { result = "ConstantReadAccess" }
@@ -342,6 +350,7 @@ class ConstantWriteAccess extends ConstantAccess {
    * constants up the namespace chain, the fully qualified name of a nested
    * constant can be ambiguous from just statically looking at the AST.
    */
+  overlay[global]
   string getAQualifiedName() { result = resolveConstantWrite(this) }
 }
 
diff --git a/ruby/ql/lib/codeql/ruby/ast/Control.qll b/ruby/ql/lib/codeql/ruby/ast/Control.qll
index 18182d8268ac..5d83e7a62fd2 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Control.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Control.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.AST
 private import internal.Control
diff --git a/ruby/ql/lib/codeql/ruby/ast/Erb.qll b/ruby/ql/lib/codeql/ruby/ast/Erb.qll
index 4dbcca734254..4def19f7ceb5 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Erb.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Erb.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.Erb
 private import internal.TreeSitter
diff --git a/ruby/ql/lib/codeql/ruby/ast/Expr.qll b/ruby/ql/lib/codeql/ruby/ast/Expr.qll
index 5f916fbec5cf..e932202e53fd 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Expr.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Expr.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import codeql.ruby.CFG
 private import internal.AST
@@ -12,6 +15,7 @@ private import internal.TreeSitter
  */
 class Expr extends Stmt, TExpr {
   /** Gets the constant value of this expression, if any. */
+  overlay[global]
   ConstantValue getConstantValue() { result = getConstantValueExpr(this) }
 }
 
@@ -425,6 +429,7 @@ class StringConcatenation extends Expr, TStringConcatenation {
    * "foo" "bar#{ n }"
    * ```
    */
+  overlay[global]
   final string getConcatenatedValueText() {
     forall(StringLiteral c | c = this.getString(_) |
       exists(c.getConstantValue().getStringlikeValue())
diff --git a/ruby/ql/lib/codeql/ruby/ast/Literal.qll b/ruby/ql/lib/codeql/ruby/ast/Literal.qll
index cdeae9e64a6e..308b2a9667cb 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Literal.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Literal.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import codeql.ruby.Regexp as RE
 private import internal.AST
@@ -41,6 +44,7 @@ class IntegerLiteral extends NumericLiteral instanceof IntegerLiteralImpl {
   /** Gets the numerical value of this integer literal. */
   final int getValue() { result = super.getValue() }
 
+  overlay[global]
   final override ConstantValue::ConstantIntegerValue getConstantValue() {
     result = NumericLiteral.super.getConstantValue()
   }
@@ -57,6 +61,7 @@ class IntegerLiteral extends NumericLiteral instanceof IntegerLiteralImpl {
  * ```
  */
 class FloatLiteral extends NumericLiteral instanceof FloatLiteralImpl {
+  overlay[global]
   final override ConstantValue::ConstantFloatValue getConstantValue() {
     result = NumericLiteral.super.getConstantValue()
   }
@@ -72,6 +77,7 @@ class FloatLiteral extends NumericLiteral instanceof FloatLiteralImpl {
  * ```
  */
 class RationalLiteral extends NumericLiteral instanceof RationalLiteralImpl {
+  overlay[global]
   final override ConstantValue::ConstantRationalValue getConstantValue() {
     result = NumericLiteral.super.getConstantValue()
   }
@@ -87,6 +93,7 @@ class RationalLiteral extends NumericLiteral instanceof RationalLiteralImpl {
  * ```
  */
 class ComplexLiteral extends NumericLiteral instanceof ComplexLiteralImpl {
+  overlay[global]
   final override ConstantValue::ConstantComplexValue getConstantValue() {
     result = NumericLiteral.super.getConstantValue()
   }
@@ -96,6 +103,7 @@ class ComplexLiteral extends NumericLiteral instanceof ComplexLiteralImpl {
 
 /** A `nil` literal. */
 class NilLiteral extends Literal instanceof NilLiteralImpl {
+  overlay[global]
   final override ConstantValue::ConstantNilValue getConstantValue() { result = TNil() }
 
   final override string getAPrimaryQlClass() { result = "NilLiteral" }
@@ -122,6 +130,7 @@ class BooleanLiteral extends Literal instanceof BooleanLiteralImpl {
   /** Gets the value of this Boolean literal. */
   boolean getValue() { result = super.getValue() }
 
+  overlay[global]
   final override ConstantValue::ConstantBooleanValue getConstantValue() {
     result = Literal.super.getConstantValue()
   }
@@ -133,6 +142,7 @@ class BooleanLiteral extends Literal instanceof BooleanLiteralImpl {
 class EncodingLiteral extends Literal instanceof EncodingLiteralImpl {
   final override string getAPrimaryQlClass() { result = "EncodingLiteral" }
 
+  overlay[global]
   final override ConstantValue::ConstantStringValue getConstantValue() {
     result = Literal.super.getConstantValue()
   }
@@ -144,6 +154,7 @@ class EncodingLiteral extends Literal instanceof EncodingLiteralImpl {
 class LineLiteral extends Literal instanceof LineLiteralImpl {
   final override string getAPrimaryQlClass() { result = "LineLiteral" }
 
+  overlay[global]
   final override ConstantValue::ConstantIntegerValue getConstantValue() {
     result = Literal.super.getConstantValue()
   }
@@ -155,6 +166,7 @@ class LineLiteral extends Literal instanceof LineLiteralImpl {
 class FileLiteral extends Literal instanceof FileLiteralImpl {
   final override string getAPrimaryQlClass() { result = "FileLiteral" }
 
+  overlay[global]
   final override ConstantValue::ConstantStringValue getConstantValue() {
     result = Literal.super.getConstantValue()
   }
@@ -166,6 +178,7 @@ class FileLiteral extends Literal instanceof FileLiteralImpl {
  */
 class StringComponent extends AstNode instanceof StringComponentImpl {
   /** Gets the constant value of this string component, if any. */
+  overlay[global]
   ConstantValue::ConstantStringValue getConstantValue() { result = TString(super.getValue()) }
 }
 
@@ -210,6 +223,7 @@ class StringInterpolationComponent extends StringComponent, StmtSequence instanc
 
   final override Stmt getStmt(int n) { toGenerated(result) = g.getChild(n) }
 
+  overlay[global]
   final override ConstantValue::ConstantStringValue getConstantValue() {
     result = StmtSequence.super.getConstantValue()
   }
@@ -257,6 +271,7 @@ class RegExpInterpolationComponent extends RegExpComponent, StmtSequence instanc
 
   final override Stmt getStmt(int n) { toGenerated(result) = g.getChild(n) }
 
+  overlay[global]
   final override ConstantValue::ConstantStringValue getConstantValue() {
     result = StmtSequence.super.getConstantValue()
   }
@@ -387,6 +402,7 @@ class RegExpLiteral extends StringlikeLiteral instanceof RegExpLiteralImpl {
   final predicate hasFreeSpacingFlag() { this.getFlagString().charAt(_) = "x" }
 
   /** Returns the root node of the parse tree of this regular expression. */
+  overlay[global]
   final RE::RegExpTerm getParsed() { result = RE::getParsedRegExp(this) }
 }
 
@@ -404,6 +420,7 @@ class SymbolLiteral extends StringlikeLiteral instanceof SymbolLiteralImpl {
     not this instanceof MethodName and result = "SymbolLiteral"
   }
 
+  overlay[global]
   final override ConstantValue::ConstantSymbolValue getConstantValue() {
     result = StringlikeLiteral.super.getConstantValue()
   }
@@ -436,6 +453,7 @@ class SubshellLiteral extends StringlikeLiteral instanceof SubshellLiteralImpl {
 class CharacterLiteral extends Literal instanceof CharacterLiteralImpl {
   final override string getAPrimaryQlClass() { result = "CharacterLiteral" }
 
+  overlay[global]
   final override ConstantValue::ConstantStringValue getConstantValue() {
     result = Literal.super.getConstantValue()
   }
diff --git a/ruby/ql/lib/codeql/ruby/ast/Method.qll b/ruby/ql/lib/codeql/ruby/ast/Method.qll
index 61ee58019d1e..147782e3d08d 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Method.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Method.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import codeql.ruby.controlflow.ControlFlowGraph
 private import internal.AST
@@ -40,18 +43,22 @@ class MethodBase extends Callable, BodyStmt, Scope, TMethodBase {
    * Holds if this method is public.
    * Methods are public by default.
    */
+  overlay[global]
   predicate isPublic() { this.getVisibility() = "public" }
 
   /** Holds if this method is private. */
+  overlay[global]
   predicate isPrivate() { this.getVisibility() = "private" }
 
   /** Holds if this method is protected. */
+  overlay[global]
   predicate isProtected() { this.getVisibility() = "protected" }
 
   /**
    * Gets a string describing the visibility of this method.
    * This is either 'public', 'private' or 'protected'.
    */
+  overlay[global]
   string getVisibility() {
     result = getVisibilityModifier(this).getVisibility()
     or
@@ -73,6 +80,7 @@ class MethodBase extends Callable, BodyStmt, Scope, TMethodBase {
  * end
  * ```
  */
+overlay[global]
 private VisibilityModifier getExplicitVisibilityModifier(Method m) {
   result.getMethodArgument() = m
   or
@@ -86,6 +94,7 @@ private VisibilityModifier getExplicitVisibilityModifier(Method m) {
  * Gets the visibility modifier that defines the visibility of method `m`, if
  * any.
  */
+overlay[global]
 private VisibilityModifier getVisibilityModifier(MethodBase mb) {
   mb =
     any(Method m |
@@ -202,6 +211,7 @@ class Method extends MethodBase, TMethod {
    * end
    * ```
    */
+  overlay[global]
   override predicate isPrivate() { super.isPrivate() }
 
   final override Parameter getParameter(int n) {
@@ -210,6 +220,7 @@ class Method extends MethodBase, TMethod {
 
   final override string toString() { result = this.getName() }
 
+  overlay[global]
   override string getVisibility() {
     result = getVisibilityModifier(this).getVisibility()
     or
@@ -223,6 +234,7 @@ class Method extends MethodBase, TMethod {
   }
 }
 
+overlay[global]
 pragma[nomagic]
 private predicate modifiesIn(VisibilityModifier vm, ModuleBase n, string name) {
   n = vm.getEnclosingModule() and
@@ -299,6 +311,7 @@ class SingletonMethod extends MethodBase, TSingletonMethod {
    * end
    * ```
    */
+  overlay[global]
   override predicate isPrivate() { super.isPrivate() }
 }
 
diff --git a/ruby/ql/lib/codeql/ruby/ast/Module.qll b/ruby/ql/lib/codeql/ruby/ast/Module.qll
index 9e2ca31ee61e..90ee8275f397 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Module.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Module.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import codeql.ruby.CFG
 private import internal.AST
@@ -8,6 +11,7 @@ private import internal.Scope
 /**
  * A representation of a run-time `module` or `class` value.
  */
+overlay[global]
 class Module extends TModule {
   /** Gets a declaration of this module, if any. */
   ModuleBase getADeclaration() { result.getModule() = this }
@@ -255,6 +259,7 @@ class ModuleBase extends BodyStmt, Scope, TModuleBase {
   }
 
   /** Gets the representation of the run-time value of this module or class. */
+  overlay[global]
   Module getModule() { none() }
 
   /**
@@ -333,6 +338,7 @@ class Toplevel extends ModuleBase, TToplevel {
     pred = "getBeginBlock" and result = this.getBeginBlock(_)
   }
 
+  overlay[global]
   final override Module getModule() { result = TResolved("Object") }
 
   final override string toString() { result = g.getLocation().getFile().getBaseName() }
@@ -405,6 +411,7 @@ class Namespace extends ModuleBase, ConstantWriteAccess, TNamespace {
    */
   override predicate hasGlobalScope() { none() }
 
+  overlay[global]
   final override Module getModule() {
     result = any(string qName | qName = namespaceDeclaration(this) | TResolved(qName))
     or
diff --git a/ruby/ql/lib/codeql/ruby/ast/Operation.qll b/ruby/ql/lib/codeql/ruby/ast/Operation.qll
index 2e005a207e3f..b9046a930b31 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Operation.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Operation.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.AST
 private import internal.TreeSitter
diff --git a/ruby/ql/lib/codeql/ruby/ast/Parameter.qll b/ruby/ql/lib/codeql/ruby/ast/Parameter.qll
index c4b233b62b6e..5b3994378c16 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Parameter.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Parameter.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.AST
 private import internal.Variable
diff --git a/ruby/ql/lib/codeql/ruby/ast/Pattern.qll b/ruby/ql/lib/codeql/ruby/ast/Pattern.qll
index ef7786640313..ac6bcc712cf9 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Pattern.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Pattern.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.AST
 private import internal.Pattern
@@ -203,6 +206,7 @@ class HashPattern extends CasePattern, THashPattern {
   }
 
   /** Gets the value for a given key name. */
+  overlay[global]
   CasePattern getValueByKey(string key) {
     exists(int i |
       this.getKey(i).getConstantValue().isStringlikeValue(key) and result = this.getValue(i)
diff --git a/ruby/ql/lib/codeql/ruby/ast/Scope.qll b/ruby/ql/lib/codeql/ruby/ast/Scope.qll
index 3e8437f79b35..334b36b583f3 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Scope.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Scope.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import internal.AST
 private import internal.Scope
diff --git a/ruby/ql/lib/codeql/ruby/ast/Statement.qll b/ruby/ql/lib/codeql/ruby/ast/Statement.qll
index 24e18fe4c362..dcd51dbb3272 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Statement.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Statement.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import codeql.ruby.CFG
 private import internal.AST
diff --git a/ruby/ql/lib/codeql/ruby/ast/Variable.qll b/ruby/ql/lib/codeql/ruby/ast/Variable.qll
index fa00cfb4cc7c..f5fb4b606046 100644
--- a/ruby/ql/lib/codeql/ruby/ast/Variable.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/Variable.qll
@@ -1,4 +1,6 @@
 /** Provides classes for modeling program variables. */
+overlay[local]
+module;
 
 private import codeql.ruby.AST
 private import internal.AST
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/AST.qll b/ruby/ql/lib/codeql/ruby/ast/internal/AST.qll
index badcf1d6c6ff..ee46fbe8b66a 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/AST.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/AST.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 import codeql.Locations
 private import TreeSitter
 private import codeql.ruby.ast.internal.Call
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Call.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Call.qll
index 5bb34989a904..4f3c236f1024 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Call.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Call.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import TreeSitter
 private import Variable
 private import codeql.ruby.AST
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Constant.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Constant.qll
index a04efc1ec94f..6fdcdc894182 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Constant.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Constant.qll
@@ -38,6 +38,7 @@ private import ExprNodes
  * constant value in some cases.
  */
 private module Propagation {
+  overlay[local]
   ExprCfgNode getSource(VariableReadAccessCfgNode read) {
     exists(Ssa::WriteDefinition def |
       def.assigns(result) and
@@ -199,6 +200,7 @@ private module Propagation {
     forex(ExprCfgNode n | n = e.getAControlFlowNode() | isComplex(n, real, imaginary))
   }
 
+  overlay[local]
   private class StringlikeLiteralWithInterpolationCfgNode extends StringlikeLiteralCfgNode {
     StringlikeLiteralWithInterpolationCfgNode() {
       this.getAComponent() =
@@ -208,6 +210,7 @@ private module Propagation {
         )
     }
 
+    overlay[global]
     pragma[nomagic]
     private string getComponentValue(int i) {
       this.getComponent(i) =
@@ -219,17 +222,20 @@ private module Propagation {
     }
 
     language[monotonicAggregates]
+    overlay[global]
     private string getValue() {
       result =
         strictconcat(int i | exists(this.getComponent(i)) | this.getComponentValue(i) order by i)
     }
 
+    overlay[global]
     pragma[nomagic]
     string getSymbolValue() {
       result = this.getValue() and
       this.getExpr() instanceof SymbolLiteral
     }
 
+    overlay[global]
     pragma[nomagic]
     string getStringValue() {
       result = this.getValue() and
@@ -237,6 +243,7 @@ private module Propagation {
       not this.getExpr() instanceof RegExpLiteral
     }
 
+    overlay[global]
     pragma[nomagic]
     string getRegExpValue(string flags) {
       result = this.getValue() and
@@ -566,6 +573,7 @@ private predicate isArrayExpr(Expr e, ArrayLiteralCfgNode arr) {
   isArrayExpr(e.(MethodCall).getReceiver(), arr)
 }
 
+overlay[local]
 private class TokenConstantAccess extends ConstantAccess, TTokenConstantAccess {
   private Ruby::Constant g;
 
@@ -577,6 +585,7 @@ private class TokenConstantAccess extends ConstantAccess, TTokenConstantAccess {
 /**
  * A constant access that has a scope resolution qualifier.
  */
+overlay[local]
 class ScopeResolutionConstantAccess extends ConstantAccess, TScopeResolutionConstantAccess {
   private Ruby::ScopeResolution g;
   private Ruby::Constant constant;
@@ -595,6 +604,7 @@ class ScopeResolutionConstantAccess extends ConstantAccess, TScopeResolutionCons
   final override predicate hasGlobalScope() { not exists(g.getScope()) }
 }
 
+overlay[local]
 private class ConstantReadAccessSynth extends ConstantAccess, TConstantReadAccessSynth {
   private string value;
 
@@ -609,6 +619,7 @@ private class ConstantReadAccessSynth extends ConstantAccess, TConstantReadAcces
   final override predicate hasGlobalScope() { value.matches("::%") }
 }
 
+overlay[local]
 private class ConstantWriteAccessSynth extends ConstantAccess, TConstantWriteAccessSynth {
   private string value;
 
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Control.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Control.qll
index 7b95d67efc45..dd57a0d197de 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Control.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Control.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import TreeSitter
 private import codeql.ruby.AST
 private import codeql.ruby.ast.internal.AST
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Erb.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Erb.qll
index 7a69bf5b783d..29960486907b 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Erb.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Erb.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 import codeql.Locations
 private import TreeSitter
 private import codeql.ruby.ast.Erb
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Expr.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Expr.qll
index ba4f9e51f4e9..fdeec446a937 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Expr.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Expr.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import codeql.ruby.CFG
 private import AST
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Literal.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Literal.qll
index 8af4673d9168..6a2df06b3490 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Literal.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Literal.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import AST
 private import Constant
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Method.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Method.qll
index 075ac5fb8fa9..c4dd1abbee02 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Method.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Method.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import AST
 private import TreeSitter
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Module.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Module.qll
index 6905dd5ff2d1..3670cc5eb98e 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Module.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Module.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import Scope as Scope
 
@@ -11,6 +14,7 @@ private string builtin() {
     ]
 }
 
+overlay[global]
 cached
 private module Cached {
   cached
@@ -215,6 +219,7 @@ private string scopeAppend(string qualifier, string name) {
  * both as a performance optimization (minimize non-linear recursion), and as a way
  * to prevent infinite recursion.
  */
+overlay[global]
 private module ResolveImpl {
   private ModuleBase enclosing(ModuleBase m, int level) {
     result = m and level = 0
@@ -583,6 +588,7 @@ private ModuleBase enclosingModuleNoBlock(Stmt node) {
   result = enclosingScopesNoBlock(Scope::scopeOfInclSynth(node))
 }
 
+overlay[global]
 private Module getAncestors(Module m) {
   result = m or
   result = getAncestors(m.getAnIncludedModule()) or
@@ -593,6 +599,7 @@ private newtype TMethodOrExpr =
   TMethod(Method m) or
   TExpr(Expr e)
 
+overlay[global]
 private TMethodOrExpr getMethodOrConst(TModule owner, string name) {
   exists(ModuleBase m | m.getModule() = owner |
     result = TMethod(m.getMethod(name))
@@ -601,12 +608,14 @@ private TMethodOrExpr getMethodOrConst(TModule owner, string name) {
   )
 }
 
+overlay[global]
 module ExposedForTestingOnly {
   Method getMethod(TModule owner, string name) { TMethod(result) = getMethodOrConst(owner, name) }
 
   Expr getConst(TModule owner, string name) { TExpr(result) = getMethodOrConst(owner, name) }
 }
 
+overlay[global]
 private TMethodOrExpr lookupMethodOrConst0(Module m, string name) {
   result = lookupMethodOrConst0(m.getAPrependedModule(), name)
   or
@@ -621,6 +630,7 @@ private TMethodOrExpr lookupMethodOrConst0(Module m, string name) {
 
 private AstNode getNode(TMethodOrExpr e) { e = TMethod(result) or e = TExpr(result) }
 
+overlay[global]
 private TMethodOrExpr lookupMethodOrConst(Module m, string name) {
   result = lookupMethodOrConst0(m, name)
   or
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Operation.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Operation.qll
index 54c763e24d39..eeec2198b625 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Operation.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Operation.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import AST
 private import TreeSitter
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Parameter.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Parameter.qll
index dc7fb8c7695e..8f07554fb0c1 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Parameter.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Parameter.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import AST
 private import TreeSitter
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Pattern.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Pattern.qll
index c59898d88eeb..a30cce32c7c6 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Pattern.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Pattern.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.AST
 private import codeql.ruby.ast.internal.Expr
 private import codeql.ruby.ast.internal.Parameter
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Scope.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Scope.qll
index 8f5bde5aeecb..9ec237012bc2 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Scope.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Scope.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import TreeSitter
 private import codeql.ruby.AST
 private import codeql.ruby.ast.internal.AST
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Synthesis.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Synthesis.qll
index 5d1ee81c0139..f2be91a63e51 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Synthesis.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Synthesis.qll
@@ -1,4 +1,6 @@
 /** Provides predicates for synthesizing AST nodes. */
+overlay[local]
+module;
 
 private import AST
 private import TreeSitter
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/TreeSitter.qll b/ruby/ql/lib/codeql/ruby/ast/internal/TreeSitter.qll
index 4d9cd901f237..dbc7b38b84e3 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/TreeSitter.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/TreeSitter.qll
@@ -23,6 +23,7 @@ private predicate discardLocation(@location_default loc) {
   )
 }
 
+overlay[local]
 module Ruby {
   /** The base class for all AST nodes */
   class AstNode extends @ruby_ast_node {
@@ -67,7 +68,6 @@ module Ruby {
   }
 
   /** Gets the file containing the given `node`. */
-  overlay[local]
   private @file getNodeFile(@ruby_ast_node node) {
     exists(@location_default loc | ruby_ast_node_location(node, loc) |
       locations_default(loc, result, _, _, _, _)
@@ -75,7 +75,6 @@ module Ruby {
   }
 
   /** Holds if `node` is in the `file` and is part of the overlay base database. */
-  overlay[local]
   private predicate discardableAstNode(@file file, @ruby_ast_node node) {
     not isOverlay() and file = getNodeFile(node)
   }
@@ -1967,6 +1966,7 @@ module Ruby {
   }
 }
 
+overlay[local]
 module Erb {
   /** The base class for all AST nodes */
   class AstNode extends @erb_ast_node {
@@ -2011,7 +2011,6 @@ module Erb {
   }
 
   /** Gets the file containing the given `node`. */
-  overlay[local]
   private @file getNodeFile(@erb_ast_node node) {
     exists(@location_default loc | erb_ast_node_location(node, loc) |
       locations_default(loc, result, _, _, _, _)
@@ -2019,7 +2018,6 @@ module Erb {
   }
 
   /** Holds if `node` is in the `file` and is part of the overlay base database. */
-  overlay[local]
   private predicate discardableAstNode(@file file, @erb_ast_node node) {
     not isOverlay() and file = getNodeFile(node)
   }
diff --git a/ruby/ql/lib/codeql/ruby/ast/internal/Variable.qll b/ruby/ql/lib/codeql/ruby/ast/internal/Variable.qll
index bea1ddadbfb3..7c130220a86b 100644
--- a/ruby/ql/lib/codeql/ruby/ast/internal/Variable.qll
+++ b/ruby/ql/lib/codeql/ruby/ast/internal/Variable.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import TreeSitter
 private import codeql.ruby.AST
 private import codeql.ruby.CFG
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/BasicBlocks.qll b/ruby/ql/lib/codeql/ruby/controlflow/BasicBlocks.qll
index f70062ad24f3..932533711984 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/BasicBlocks.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/BasicBlocks.qll
@@ -1,4 +1,6 @@
 /** Provides classes representing basic blocks. */
+overlay[local]
+module;
 
 private import codeql.ruby.AST
 private import codeql.ruby.ast.internal.AST
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/CfgNodes.qll b/ruby/ql/lib/codeql/ruby/controlflow/CfgNodes.qll
index c822450bf89c..2a3d23056f4e 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/CfgNodes.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/CfgNodes.qll
@@ -1,4 +1,6 @@
 /** Provides classes representing nodes in a control flow graph. */
+overlay[local]
+module;
 
 private import codeql.ruby.AST
 private import codeql.ruby.controlflow.BasicBlocks
@@ -36,11 +38,13 @@ class ExitNode extends CfgNode, CfgImpl::ExitNode {
  */
 class AstCfgNode extends CfgNode, CfgImpl::AstCfgNode {
   /** Gets the name of the primary QL class for this node. */
+  overlay[global]
   override string getAPrimaryQlClass() { result = "AstCfgNode" }
 }
 
 /** A control-flow node that wraps an AST expression. */
 class ExprCfgNode extends AstCfgNode {
+  overlay[global]
   override string getAPrimaryQlClass() { result = "ExprCfgNode" }
 
   Expr e;
@@ -51,6 +55,7 @@ class ExprCfgNode extends AstCfgNode {
   Expr getExpr() { result = e }
 
   /** Gets the constant value of this expression, if any. */
+  overlay[global]
   ConstantValue getConstantValue() { result = getConstantValue(this) }
 }
 
@@ -76,6 +81,7 @@ class StringComponentCfgNode extends AstCfgNode {
   StringComponentCfgNode() { this.getAstNode() instanceof StringComponent }
 
   /** Gets the constant value of this string component. */
+  overlay[global]
   ConstantValue getConstantValue() {
     result = this.getAstNode().(StringComponent).getConstantValue()
   }
@@ -297,6 +303,7 @@ module ExprNodes {
 
   /** A control-flow node that wraps a `Call` AST expression. */
   class CallCfgNode extends ExprCfgNode {
+    overlay[global]
     override string getAPrimaryQlClass() { result = "CallCfgNode" }
 
     override CallExprChildMapping e;
@@ -310,6 +317,7 @@ module ExprNodes {
     final ExprCfgNode getAnArgument() { result = this.getArgument(_) }
 
     /** Gets the keyword argument whose key is `keyword` of this call. */
+    overlay[global]
     final ExprCfgNode getKeywordArgument(string keyword) {
       exists(PairCfgNode n |
         e.hasCfgChild(e.getAnArgument(), this, n) and
@@ -338,6 +346,7 @@ module ExprNodes {
 
   /** A control-flow node that wraps a `MethodCall` AST expression. */
   class MethodCallCfgNode extends CallCfgNode {
+    overlay[global]
     override string getAPrimaryQlClass() { result = "MethodCallCfgNode" }
 
     MethodCallCfgNode() { super.getExpr() instanceof MethodCall }
@@ -842,6 +851,7 @@ module ExprNodes {
       this.getAstNode() instanceof StringInterpolationComponent
     }
 
+    overlay[global]
     final override ConstantValue getConstantValue() {
       result = StmtSequenceCfgNode.super.getConstantValue()
     }
@@ -855,6 +865,7 @@ module ExprNodes {
       this.getAstNode() instanceof RegExpInterpolationComponent
     }
 
+    overlay[global]
     final override ConstantValue getConstantValue() {
       result = StmtSequenceCfgNode.super.getConstantValue()
     }
@@ -946,6 +957,7 @@ module ExprNodes {
    * into calls to `Array.[]`, so this includes both desugared calls as well as
    * explicit calls.
    */
+  overlay[global]
   class ArrayLiteralCfgNode extends MethodCallCfgNode {
     override string getAPrimaryQlClass() { result = "ArrayLiteralCfgNode" }
 
@@ -963,6 +975,7 @@ module ExprNodes {
    * into calls to `Hash.[]`, so this includes both desugared calls as well as
    * explicit calls.
    */
+  overlay[global]
   class HashLiteralCfgNode extends MethodCallCfgNode {
     override string getAPrimaryQlClass() { result = "HashLiteralCfgNode" }
 
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll b/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll
index dee31d8e901b..1d3632ba1c07 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll
@@ -1,4 +1,6 @@
 /** Provides classes representing the control flow graph. */
+overlay[local]
+module;
 
 private import codeql.ruby.AST
 private import codeql.ruby.controlflow.BasicBlocks
@@ -35,6 +37,7 @@ class CfgScope extends Scope instanceof CfgImpl::CfgScopeImpl {
  */
 class CfgNode extends CfgImpl::Node {
   /** Gets the name of the primary QL class for this node. */
+  overlay[global]
   string getAPrimaryQlClass() { none() }
 
   /** Gets the file of this control flow node. */
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/internal/Completion.qll b/ruby/ql/lib/codeql/ruby/controlflow/internal/Completion.qll
index 83ea11e9d230..b8edf83c20df 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/internal/Completion.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/internal/Completion.qll
@@ -3,6 +3,8 @@
  *
  * A completion represents how a statement or expression terminates.
  */
+overlay[local]
+module;
 
 private import codeql.ruby.AST
 private import codeql.ruby.ast.internal.AST
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll b/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll
index dd672ba982d7..d0d418a839f6 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll
@@ -2,6 +2,8 @@
  * Provides an implementation for constructing control-flow graphs (CFGs) from
  * abstract syntax trees (ASTs), using the shared library from `codeql.controlflow.Cfg`.
  */
+overlay[local]
+module;
 
 private import codeql.controlflow.Cfg as CfgShared
 private import codeql.ruby.AST
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/internal/Guards.qll b/ruby/ql/lib/codeql/ruby/controlflow/internal/Guards.qll
index 1161a061581c..a60102e017c6 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/internal/Guards.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/internal/Guards.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ruby.CFG
 
 /** Holds if the guard `guard` controls block `bb` upon evaluating to `branch`. */
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/internal/NonReturning.qll b/ruby/ql/lib/codeql/ruby/controlflow/internal/NonReturning.qll
index e1927a0b1c97..45b299a5d2b7 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/internal/NonReturning.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/internal/NonReturning.qll
@@ -1,4 +1,6 @@
 /** Provides a simple analysis for identifying calls that will not return. */
+overlay[local]
+module;
 
 private import codeql.ruby.AST
 private import Completion
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/internal/Splitting.qll b/ruby/ql/lib/codeql/ruby/controlflow/internal/Splitting.qll
index 5331a3d26b64..146d5927479d 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/internal/Splitting.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/internal/Splitting.qll
@@ -1,6 +1,8 @@
 /**
  * Provides classes and predicates relevant for splitting the control flow graph.
  */
+overlay[local]
+module;
 
 private import codeql.ruby.AST as Ast
 private import Completion as Comp
diff --git a/ruby/ql/lib/codeql/ruby/dataflow/SSA.qll b/ruby/ql/lib/codeql/ruby/dataflow/SSA.qll
index 07721d333341..1478d9ed9d6b 100644
--- a/ruby/ql/lib/codeql/ruby/dataflow/SSA.qll
+++ b/ruby/ql/lib/codeql/ruby/dataflow/SSA.qll
@@ -1,6 +1,8 @@
 /**
  * Provides the module `Ssa` for working with static single assignment (SSA) form.
  */
+overlay[local]
+module;
 
 /**
  * Provides classes for working with static single assignment (SSA) form.
diff --git a/ruby/ql/lib/codeql/ruby/dataflow/internal/SsaImpl.qll b/ruby/ql/lib/codeql/ruby/dataflow/internal/SsaImpl.qll
index adbec18be640..5d69810ed9a1 100644
--- a/ruby/ql/lib/codeql/ruby/dataflow/internal/SsaImpl.qll
+++ b/ruby/ql/lib/codeql/ruby/dataflow/internal/SsaImpl.qll
@@ -1,3 +1,6 @@
+overlay[local]
+module;
+
 private import codeql.ssa.Ssa as SsaImplCommon
 private import codeql.ruby.AST
 private import codeql.ruby.CFG as Cfg
@@ -375,10 +378,12 @@ private module Cached {
     Impl::uncertainWriteDefinitionInput(def, result)
   }
 
+  overlay[global]
   cached
   module DataFlowIntegration {
     import DataFlowIntegrationImpl
 
+    overlay[local]
     cached
     predicate localFlowStep(
       SsaInput::SourceVariable v, Node nodeFrom, Node nodeTo, boolean isUseStep
@@ -469,19 +474,24 @@ class ParameterExt extends TParameterExt {
   }
 }
 
+overlay[global]
 private module DataFlowIntegrationInput implements Impl::DataFlowIntegrationInputSig {
   private import codeql.ruby.controlflow.internal.Guards as Guards
 
+  overlay[local]
   class Expr extends Cfg::CfgNodes::ExprCfgNode {
     predicate hasCfgNode(SsaInput::BasicBlock bb, int i) { this = bb.getNode(i) }
   }
 
+  overlay[local]
   Expr getARead(Definition def) { result = Cached::getARead(def) }
 
+  overlay[local]
   predicate ssaDefHasSource(WriteDefinition def) {
     any(ParameterExt p).isInitializedBy(def) or def.(Ssa::WriteDefinition).assigns(_)
   }
 
+  overlay[local]
   class Guard extends Cfg::CfgNodes::AstCfgNode {
     /**
      * Holds if the evaluation of this guard to `branch` corresponds to the edge
@@ -506,6 +516,7 @@ private module DataFlowIntegrationInput implements Impl::DataFlowIntegrationInpu
   }
 
   /** Holds if the guard `guard` controls block `bb` upon evaluating to `branch`. */
+  overlay[local]
   predicate guardDirectlyControlsBlock(Guard guard, SsaInput::BasicBlock bb, boolean branch) {
     Guards::guardControlsBlock(guard, bb, branch)
   }
diff --git a/ruby/ql/lib/qlpack.yml b/ruby/ql/lib/qlpack.yml
index ef9f163cbd91..9a1fd81630ed 100644
--- a/ruby/ql/lib/qlpack.yml
+++ b/ruby/ql/lib/qlpack.yml
@@ -17,3 +17,4 @@ dataExtensions:
   - codeql/ruby/frameworks/**/model.yml
   - codeql/ruby/frameworks/**/*.model.yml
 warnOnImplicitThis: true
+compileForOverlayEval: true
diff --git a/shared/tree-sitter-extractor/src/generator/mod.rs b/shared/tree-sitter-extractor/src/generator/mod.rs
index d9e6e00a1211..5e58611092b2 100644
--- a/shared/tree-sitter-extractor/src/generator/mod.rs
+++ b/shared/tree-sitter-extractor/src/generator/mod.rs
@@ -120,6 +120,7 @@ pub fn generate(
                 qldoc: None,
                 name: &language.name,
                 body,
+                overlay: Some(ql::OverlayAnnotation::Local),
             })],
         )?;
     }
diff --git a/shared/tree-sitter-extractor/src/generator/ql.rs b/shared/tree-sitter-extractor/src/generator/ql.rs
index e4c87b61bdb8..b1e319afb1e8 100644
--- a/shared/tree-sitter-extractor/src/generator/ql.rs
+++ b/shared/tree-sitter-extractor/src/generator/ql.rs
@@ -95,6 +95,7 @@ pub struct Module<'a> {
     pub qldoc: Option<String>,
     pub name: &'a str,
     pub body: Vec<TopLevel<'a>>,
+    pub overlay: Option<OverlayAnnotation>,
 }
 
 impl fmt::Display for Module<'_> {
@@ -102,6 +103,14 @@ impl fmt::Display for Module<'_> {
         if let Some(qldoc) = &self.qldoc {
             write!(f, "/** {} */", qldoc)?;
         }
+        if let Some(overlay_annotation) = &self.overlay {
+            write!(f, "overlay[")?;
+            match overlay_annotation {
+                OverlayAnnotation::Local => write!(f, "local")?,
+                OverlayAnnotation::DiscardEntity => write!(f, "discard_entity")?,
+            }
+            write!(f, "] ")?;
+        }
         writeln!(f, "module {} {{ ", self.name)?;
         for decl in &self.body {
             writeln!(f, "  {}", decl)?;
diff --git a/shared/tree-sitter-extractor/src/generator/ql_gen.rs b/shared/tree-sitter-extractor/src/generator/ql_gen.rs
index 8b6c9c18c6f8..2cfaf5715caa 100644
--- a/shared/tree-sitter-extractor/src/generator/ql_gen.rs
+++ b/shared/tree-sitter-extractor/src/generator/ql_gen.rs
@@ -286,7 +286,7 @@ pub fn create_get_node_file_predicate<'a>(
         overridden: false,
         is_private: true,
         is_final: false,
-        overlay: Some(ql::OverlayAnnotation::Local),
+        overlay: None,
         return_type: Some(ql::Type::At("file")),
         formal_parameters: vec![ql::FormalParameter {
             name: "node",
@@ -327,7 +327,7 @@ pub fn create_discardable_ast_node_predicate(ast_node_name: &str) -> ql::Predica
         overridden: false,
         is_private: true,
         is_final: false,
-        overlay: Some(ql::OverlayAnnotation::Local),
+        overlay: None,
         return_type: None,
         formal_parameters: vec![
             ql::FormalParameter {