diff --git a/internal/checker/checker.go b/internal/checker/checker.go
index 020fe61193..ac40693755 100644
--- a/internal/checker/checker.go
+++ b/internal/checker/checker.go
@@ -26447,7 +26447,14 @@ func (c *Checker) getCrossProductUnionSize(types []*Type) int {
 	for _, t := range types {
 		switch {
 		case t.flags&TypeFlagsUnion != 0:
-			size *= len(t.Types())
+			n := len(t.Types())
+			// Cap the result to avoid integer overflow when computing the cross product of many large unions.
+			// In TypeScript, number overflow produces Infinity which naturally exceeds the limit check;
+			// in Go, we must guard against int wrapping to zero or negative.
+			if n > 0 && size > math.MaxInt/n {
+				return math.MaxInt
+			}
+			size *= n
 		case t.flags&TypeFlagsNever != 0:
 			return 0
 		}
diff --git a/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.errors.txt b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.errors.txt
new file mode 100644
index 0000000000..9c3f8ba286
--- /dev/null
+++ b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.errors.txt
@@ -0,0 +1,10 @@
+templateLiteralTypeTooComplex.ts(3,10): error TS2590: Expression produces a union type that is too complex to represent.
+
+
+==== templateLiteralTypeTooComplex.ts (1 errors) ====
+    // Large template literal types with combinatorial explosion should produce an error, not hang.
+    type N = 0 | 1 | 2 | 3;
+    type T = `${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}`;
+             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2590: Expression produces a union type that is too complex to represent.
+    
\ No newline at end of file
diff --git a/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.js b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.js
new file mode 100644
index 0000000000..56d95ddb74
--- /dev/null
+++ b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.js
@@ -0,0 +1,10 @@
+//// [tests/cases/compiler/templateLiteralTypeTooComplex.ts] ////
+
+//// [templateLiteralTypeTooComplex.ts]
+// Large template literal types with combinatorial explosion should produce an error, not hang.
+type N = 0 | 1 | 2 | 3;
+type T = `${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}`;
+
+
+//// [templateLiteralTypeTooComplex.js]
+"use strict";
diff --git a/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.symbols b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.symbols
new file mode 100644
index 0000000000..6b9ef9e007
--- /dev/null
+++ b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.symbols
@@ -0,0 +1,59 @@
+//// [tests/cases/compiler/templateLiteralTypeTooComplex.ts] ////
+
+=== templateLiteralTypeTooComplex.ts ===
+// Large template literal types with combinatorial explosion should produce an error, not hang.
+type N = 0 | 1 | 2 | 3;
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+
+type T = `${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}`;
+>T : Symbol(T, Decl(templateLiteralTypeTooComplex.ts, 1, 23))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+>N : Symbol(N, Decl(templateLiteralTypeTooComplex.ts, 0, 0))
+
diff --git a/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.types b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.types
new file mode 100644
index 0000000000..ef80420132
--- /dev/null
+++ b/testdata/baselines/reference/compiler/templateLiteralTypeTooComplex.types
@@ -0,0 +1,10 @@
+//// [tests/cases/compiler/templateLiteralTypeTooComplex.ts] ////
+
+=== templateLiteralTypeTooComplex.ts ===
+// Large template literal types with combinatorial explosion should produce an error, not hang.
+type N = 0 | 1 | 2 | 3;
+>N : N
+
+type T = `${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}`;
+>T : any
+
diff --git a/testdata/tests/cases/compiler/templateLiteralTypeTooComplex.ts b/testdata/tests/cases/compiler/templateLiteralTypeTooComplex.ts
new file mode 100644
index 0000000000..e1569f9d4f
--- /dev/null
+++ b/testdata/tests/cases/compiler/templateLiteralTypeTooComplex.ts
@@ -0,0 +1,5 @@
+// @strict: true
+
+// Large template literal types with combinatorial explosion should produce an error, not hang.
+type N = 0 | 1 | 2 | 3;
+type T = `${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}${N}`;