diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPVisitor.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPVisitor.java
index 02d25f564e8..37f1353c852 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPVisitor.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPVisitor.java
@@ -194,6 +194,7 @@ import org.eclipse.cdt.internal.core.dom.parser.ASTInternal;
 import org.eclipse.cdt.internal.core.dom.parser.ASTQueries;
 import org.eclipse.cdt.internal.core.dom.parser.ASTTranslationUnit;
 import org.eclipse.cdt.internal.core.dom.parser.IASTInternalScope;
+import org.eclipse.cdt.internal.core.dom.parser.ITypeContainer;
 import org.eclipse.cdt.internal.core.dom.parser.IntegralValue;
 import org.eclipse.cdt.internal.core.dom.parser.ProblemBinding;
 import org.eclipse.cdt.internal.core.dom.parser.ProblemType;
@@ -2321,11 +2322,11 @@ public class CPPVisitor extends ASTQueries {
 			if (initClause instanceof IASTEqualsInitializer) {
 				initClause = ((IASTEqualsInitializer) initClause).getInitializerClause();
 				if (initClause instanceof IASTLiteralExpression && SemanticUtil.isConst(type)) {
-					IType t = SemanticUtil.getNestedType(type, TDEF | ALLCVQ);
-					if (t instanceof CPPBasicType) {
-						IValue v = SemanticUtil.getValueOfInitializer(declarator.getInitializer(), t);
-						if (v.numberValue() != null)
-							((CPPBasicType) t).setAssociatedNumericalValue(v.numberValue().longValue());
+					// The check here avoids performing the computation in getValueOfInitialize()
+					// in cases where we wouldn't use it anyways because we don't have a CPPBasicType.
+					if (SemanticUtil.getNestedType(type, TDEF | ALLCVQ) instanceof CPPBasicType) {
+						type = associateTypeWithValue(type,
+								SemanticUtil.getValueOfInitializer(declarator.getInitializer(), type));
 					}
 				}
 			}
@@ -2349,6 +2350,42 @@ public class CPPVisitor extends ASTQueries {
 		}
 	}
 
+	/**
+	 * Returns an IType representing the same type as the argument, but
+	 * which also knows its value.
+	 *
+	 * This only has an effect for built-in types (modulo cv-qualification
+	 * and typedefs), and in cases where the a concrete numerical value
+	 * is known.
+	 *
+	 * The returned IType object may be different from the argument.
+	 */
+	public static IType associateTypeWithValue(IType type, IValue value) {
+		Number numberValue = value.numberValue();
+		if (numberValue != null) {
+			return associateTypeWithValue(type, numberValue.longValue());
+		}
+		return type;
+	}
+
+	private static IType associateTypeWithValue(IType type, long value) {
+		if (type instanceof ITypeContainer) {
+			ITypeContainer typeContainer = (ITypeContainer) type;
+			IType oldInner = typeContainer.getType();
+			IType newInner = associateTypeWithValue(oldInner, value);
+			if (oldInner != newInner) {
+				ITypeContainer clone = (ITypeContainer) typeContainer.clone();
+				clone.setType(newInner);
+				return clone;
+			}
+		} else if (type instanceof CPPBasicType) {
+			CPPBasicType clone = ((CPPBasicType) type).clone();
+			clone.setAssociatedNumericalValue(value);
+			return clone;
+		}
+		return type;
+	}
+
 	private static IType createAutoParameterType(IASTDeclSpecifier declSpec, IASTDeclarator declarator,
 			ICPPASTParameterDeclaration declaration, PlaceholderKind placeholder) {
 		// decltype(auto) is not allowed in parameters.
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalUnaryTypeID.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalUnaryTypeID.java
index 429ea286340..5d8348e5ab8 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalUnaryTypeID.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalUnaryTypeID.java
@@ -161,15 +161,8 @@ public class EvalUnaryTypeID extends CPPDependentEvaluation {
 		case op_sizeofParameterPack:
 		case op_alignof:
 			IType result = (IType) CPPVisitor.get_SIZE_T().clone();
-			IType simplifiedResult = SemanticUtil.getSimplifiedType(result);
-			if (simplifiedResult instanceof CPPBasicType) {
-				CPPBasicType t = (CPPBasicType) simplifiedResult;
-				IValue value = getValue();
-				if (value != null && value.numberValue() != null) {
-					t.setAssociatedNumericalValue(value.numberValue().longValue());
-				}
-				// We're still returning 'result', which is now modified.
-				// This preserves the 'size_t' typedef.
+			if (SemanticUtil.getSimplifiedType(result) instanceof CPPBasicType) {
+				result = CPPVisitor.associateTypeWithValue(result, getValue());
 			}
 			return result;
 		case op_typeid: