diff --git a/common/BUILD b/common/BUILD
index a1d4ac3bd..937a27f45 100644
--- a/common/BUILD
+++ b/common/BUILD
@@ -640,8 +640,8 @@ cc_test(
     deps = [
         ":source",
         "//internal:testing",
+        "@com_google_absl//absl/status",
         "@com_google_absl//absl/strings:cord",
-        "@com_google_absl//absl/types:optional",
     ],
 )
 
diff --git a/common/source.cc b/common/source.cc
index 81b1ada9a..e7e09d919 100644
--- a/common/source.cc
+++ b/common/source.cc
@@ -307,12 +307,18 @@ struct SourceTextTraits<absl::Cord> {
 
 template <typename T>
 absl::StatusOr<SourcePtr> NewSourceImpl(std::string description, const T& text,
-                                        const size_t text_size) {
+                                        const size_t text_size,
+                                        const size_t max_codepoints) {
   if (ABSL_PREDICT_FALSE(
           text_size >
           static_cast<size_t>(std::numeric_limits<int32_t>::max()))) {
     return absl::InvalidArgumentError("expression larger than 2GiB limit");
   }
+  if ((text_size >> 2) > max_codepoints) {
+    // If byte size is 4 times the codepoint limit, then definitely exceeded.
+    return absl::InvalidArgumentError(absl::StrCat(
+        "expression is larger than codepoint limit ", max_codepoints));
+  }
   using Traits = SourceTextTraits<T>;
   size_t index = 0;
   typename Traits::iterator_type it = Traits::Begin(text);
@@ -324,6 +330,10 @@ absl::StatusOr<SourcePtr> NewSourceImpl(std::string description, const T& text,
   std::vector<char32_t> data32;
   absl::InlinedVector<SourcePosition, 1> line_offsets;
   while (index < text_size) {
+    if (offset >= max_codepoints) {
+      return absl::InvalidArgumentError(absl::StrCat(
+          "expression is larger than codepoint limit ", max_codepoints));
+    }
     std::tie(code_point, code_units) = cel::internal::Utf8Decode(it);
     if (ABSL_PREDICT_FALSE(code_point ==
                                cel::internal::kUnicodeReplacementCharacter &&
@@ -375,6 +385,10 @@ absl::StatusOr<SourcePtr> NewSourceImpl(std::string description, const T& text,
       std::move(description), std::move(line_offsets), Traits::ToVector(text));
 latin1:
   while (index < text_size) {
+    if (offset >= max_codepoints) {
+      return absl::InvalidArgumentError(absl::StrCat(
+          "expression is larger than codepoint limit ", max_codepoints));
+    }
     std::tie(code_point, code_units) = internal::Utf8Decode(it);
     if (ABSL_PREDICT_FALSE(code_point ==
                                internal::kUnicodeReplacementCharacter &&
@@ -420,6 +434,10 @@ absl::StatusOr<SourcePtr> NewSourceImpl(std::string description, const T& text,
       std::move(description), std::move(line_offsets), std::move(data8));
 basic:
   while (index < text_size) {
+    if (offset >= max_codepoints) {
+      return absl::InvalidArgumentError(absl::StrCat(
+          "expression is larger than codepoint limit ", max_codepoints));
+    }
     std::tie(code_point, code_units) = internal::Utf8Decode(it);
     if (ABSL_PREDICT_FALSE(code_point ==
                                internal::kUnicodeReplacementCharacter &&
@@ -453,6 +471,10 @@ absl::StatusOr<SourcePtr> NewSourceImpl(std::string description, const T& text,
       std::move(description), std::move(line_offsets), std::move(data16));
 supplemental:
   while (index < text_size) {
+    if (offset >= max_codepoints) {
+      return absl::InvalidArgumentError(absl::StrCat(
+          "expression is larger than codepoint limit ", max_codepoints));
+    }
     std::tie(code_point, code_units) = internal::Utf8Decode(it);
     if (ABSL_PREDICT_FALSE(code_point ==
                                internal::kUnicodeReplacementCharacter &&
@@ -631,16 +653,27 @@ absl::Span<const SourcePosition> SourceSubrange::line_offsets() const {
   return absl::MakeConstSpan(line_offsets_);
 }
 
+static size_t ClampLimit(int value) {
+  if (value < 0) {
+    return std::numeric_limits<size_t>::max();
+  }
+  return static_cast<size_t>(value);
+}
+
 absl::StatusOr<absl_nonnull SourcePtr> NewSource(absl::string_view content,
-                                                 std::string description) {
+                                                 std::string description,
+                                                 const SourceOptions& options) {
   return common_internal::NewSourceImpl(std::move(description), content,
-                                        content.size());
+                                        content.size(),
+                                        ClampLimit(options.max_codepoint_size));
 }
 
 absl::StatusOr<absl_nonnull SourcePtr> NewSource(const absl::Cord& content,
-                                                 std::string description) {
+                                                 std::string description,
+                                                 const SourceOptions& options) {
   return common_internal::NewSourceImpl(std::move(description), content,
-                                        content.size());
+                                        content.size(),
+                                        ClampLimit(options.max_codepoint_size));
 }
 
 }  // namespace cel
diff --git a/common/source.h b/common/source.h
index b3968453f..190c750cc 100644
--- a/common/source.h
+++ b/common/source.h
@@ -221,11 +221,40 @@ class SourceSubrange final : public Source {
 
 using SourcePtr = std::unique_ptr<Source>;
 
-absl::StatusOr<absl_nonnull SourcePtr> NewSource(
-    absl::string_view content, std::string description = "<input>");
+struct SourceOptions {
+  // The maximum number of code points allowed in the source.
+  // A negative value indicates no limit (though still limited by
+  // int32_t max value).
+  int max_codepoint_size = 100'000;
+};
+
+absl::StatusOr<absl_nonnull SourcePtr> NewSource(absl::string_view content,
+                                                 std::string description,
+                                                 const SourceOptions& options);
+
+absl::StatusOr<absl_nonnull SourcePtr> NewSource(const absl::Cord& content,
+                                                 std::string description,
+                                                 const SourceOptions& options);
+
+inline absl::StatusOr<absl_nonnull SourcePtr> NewSource(
+    absl::string_view content, std::string description) {
+  return NewSource(content, std::move(description), SourceOptions{});
+}
 
-absl::StatusOr<absl_nonnull SourcePtr> NewSource(
-    const absl::Cord& content, std::string description = "<input>");
+inline absl::StatusOr<absl_nonnull SourcePtr> NewSource(
+    const absl::Cord& content, std::string description) {
+  return NewSource(content, std::move(description), SourceOptions{});
+}
+
+inline absl::StatusOr<absl_nonnull SourcePtr> NewSource(
+    absl::string_view content) {
+  return NewSource(content, "<input>", SourceOptions{});
+}
+
+inline absl::StatusOr<absl_nonnull SourcePtr> NewSource(
+    const absl::Cord& content) {
+  return NewSource(content, "<input>", SourceOptions{});
+}
 
 }  // namespace cel
 
diff --git a/common/source_test.cc b/common/source_test.cc
index e620d3dd8..8315fd517 100644
--- a/common/source_test.cc
+++ b/common/source_test.cc
@@ -14,8 +14,11 @@
 
 #include "common/source.h"
 
+#include <cstdint>
+#include <optional>
+
+#include "absl/status/status.h"
 #include "absl/strings/cord.h"
-#include "absl/types/optional.h"
 #include "internal/testing.h"
 
 namespace cel {
@@ -262,5 +265,51 @@ TEST(SourceSubrange, LineOffsetsMiddleSubrange) {
   EXPECT_THAT(subrange.line_offsets(), ElementsAre(6, 10));
 }
 
+TEST(StringSource, CodepointLimitExceeded) {
+  SourceOptions options;
+  options.max_codepoint_size = 5;
+
+  EXPECT_THAT(
+      NewSource("123456", "test", options),
+      ::absl_testing::StatusIs(
+          absl::StatusCode::kInvalidArgument,
+          ::testing::HasSubstr("expression is larger than codepoint limit 5")));
+
+  ASSERT_OK_AND_ASSIGN(auto source, NewSource("12345", "test", options));
+  EXPECT_THAT(source->content().ToString(), ::testing::Eq("12345"));
+}
+
+TEST(StringSource, CodepointLimitMultibyteUtf8) {
+  SourceOptions options;
+  options.max_codepoint_size = 5;
+
+  // "Ｈｅｌｌｏ" consists of 5 full-width Unicode characters (15 bytes in
+  // UTF-8).
+  ASSERT_OK_AND_ASSIGN(auto source, NewSource("Ｈｅｌｌｏ", "test", options));
+  EXPECT_THAT(source->content().ToString(), ::testing::Eq("Ｈｅｌｌｏ"));
+
+  options.max_codepoint_size = 4;
+  EXPECT_THAT(
+      NewSource("Ｈｅｌｌｏ", "test", options),
+      ::absl_testing::StatusIs(
+          absl::StatusCode::kInvalidArgument,
+          ::testing::HasSubstr("expression is larger than codepoint limit 4")));
+}
+
+TEST(CordSource, CodepointLimitExceeded) {
+  SourceOptions options;
+  options.max_codepoint_size = 5;
+
+  EXPECT_THAT(
+      NewSource(absl::Cord("123456"), "test", options),
+      ::absl_testing::StatusIs(
+          absl::StatusCode::kInvalidArgument,
+          ::testing::HasSubstr("expression is larger than codepoint limit 5")));
+
+  ASSERT_OK_AND_ASSIGN(auto source,
+                       NewSource(absl::Cord("12345"), "test", options));
+  EXPECT_THAT(source->content().ToString(), ::testing::Eq("12345"));
+}
+
 }  // namespace
 }  // namespace cel
diff --git a/compiler/compiler.h b/compiler/compiler.h
index 174912f71..58c60027b 100644
--- a/compiler/compiler.h
+++ b/compiler/compiler.h
@@ -178,8 +178,8 @@ class Compiler {
 inline absl::StatusOr<ValidationResult> Compiler::Compile(
     absl::string_view source, absl::string_view description,
     google::protobuf::Arena* absl_nullable arena) const {
-  absl::StatusOr<SourcePtr> source_obj =
-      NewSource(source, std::string(description));
+  absl::StatusOr<std::unique_ptr<Source>> source_obj =
+      GetParser().PrepareSource(source, description);
   if (!source_obj.ok()) {
     return source_obj.status();
   }
diff --git a/compiler/compiler_factory_test.cc b/compiler/compiler_factory_test.cc
index 3f83f5bf2..f90cc4862 100644
--- a/compiler/compiler_factory_test.cc
+++ b/compiler/compiler_factory_test.cc
@@ -441,5 +441,24 @@ TEST(CompilerFactoryTest, CompileSourceOverload) {
   EXPECT_TRUE(result.IsValid());
 }
 
+TEST(CompilerFactoryTest, CodepointLimitExceeded) {
+  CompilerOptions options;
+  options.parser_options.expression_size_codepoint_limit = 10;
+  ASSERT_OK_AND_ASSIGN(
+      auto builder,
+      NewCompilerBuilder(cel::internal::GetSharedTestingDescriptorPool(),
+                         options));
+  ASSERT_OK_AND_ASSIGN(auto compiler, builder->Build());
+
+  EXPECT_THAT(
+      compiler->Compile("123456789012345", "test.cel"),
+      StatusIs(absl::StatusCode::kInvalidArgument,
+               HasSubstr("expression is larger than codepoint limit 10")));
+
+  ASSERT_OK_AND_ASSIGN(ValidationResult result,
+                       compiler->Compile("1234567890", "test.cel"));
+  EXPECT_TRUE(result.IsValid());
+}
+
 }  // namespace
 }  // namespace cel
diff --git a/parser/internal/pratt_parser.cc b/parser/internal/pratt_parser.cc
index 0ccc28c15..3f59e5065 100644
--- a/parser/internal/pratt_parser.cc
+++ b/parser/internal/pratt_parser.cc
@@ -163,6 +163,14 @@ absl::StatusOr<std::unique_ptr<cel::Ast>> PrattParserImpl::ParseImpl(
   return PrattParseImpl(source, macro_registry_, options_, parse_issues);
 }
 
+absl::StatusOr<std::unique_ptr<cel::Source>> PrattParserImpl::PrepareSourceImpl(
+    absl::string_view input, absl::string_view description) const {
+  return cel::NewSource(
+      input, std::string(description),
+      cel::SourceOptions{.max_codepoint_size =
+                             options_.expression_size_codepoint_limit});
+}
+
 absl::StatusOr<std::unique_ptr<cel::Ast>> PrattParseImpl(
     const cel::Source& source, const cel::MacroRegistry& registry,
     const ParserOptions& options, std::vector<cel::ParseIssue>* parse_issues) {
diff --git a/parser/internal/pratt_parser.h b/parser/internal/pratt_parser.h
index 469f48aec..006a10c28 100644
--- a/parser/internal/pratt_parser.h
+++ b/parser/internal/pratt_parser.h
@@ -59,6 +59,9 @@ class PrattParserImpl final : public cel::Parser {
       const cel::Source& source,
       std::vector<cel::ParseIssue>* absl_nullable parse_issues) const override;
 
+  absl::StatusOr<std::unique_ptr<cel::Source>> PrepareSourceImpl(
+      absl::string_view input, absl::string_view description) const override;
+
   std::unique_ptr<cel::ParserBuilder> ToBuilder() const override;
 
  private:
diff --git a/parser/parser.cc b/parser/parser.cc
index 9bc471fdf..28923e02d 100644
--- a/parser/parser.cc
+++ b/parser/parser.cc
@@ -1781,6 +1781,14 @@ class ParserImpl : public cel::Parser {
                                       std::move(parse_result.source_info));
   }
 
+  absl::StatusOr<std::unique_ptr<cel::Source>> PrepareSourceImpl(
+      absl::string_view input, absl::string_view description) const override {
+    return cel::NewSource(
+        input, std::string(description),
+        cel::SourceOptions{.max_codepoint_size =
+                               options_.expression_size_codepoint_limit});
+  }
+
   std::unique_ptr<cel::ParserBuilder> ToBuilder() const override;
 
  private:
diff --git a/parser/parser_interface.h b/parser/parser_interface.h
index ad6e8ca84..eb902c041 100644
--- a/parser/parser_interface.h
+++ b/parser/parser_interface.h
@@ -114,6 +114,14 @@ class Parser {
   absl::StatusOr<std::unique_ptr<cel::Ast>> Parse(
       const cel::Source& source, std::vector<ParseIssue>* issues) const;
 
+  // Returns a Source object from the given input.
+  // Validates that the input is well-formed utf-8 and within the configured
+  // source limits.
+  absl::StatusOr<std::unique_ptr<cel::Source>> PrepareSource(
+      absl::string_view input, absl::string_view description) const;
+  absl::StatusOr<std::unique_ptr<cel::Source>> PrepareSource(
+      absl::string_view input) const;
+
   // Returns a builder initialized with the configuration of this parser.
   virtual std::unique_ptr<ParserBuilder> ToBuilder() const = 0;
 
@@ -121,6 +129,9 @@ class Parser {
   virtual absl::StatusOr<std::unique_ptr<cel::Ast>> ParseImpl(
       const cel::Source& source,
       std::vector<ParseIssue>* absl_nullable parse_issues) const = 0;
+
+  virtual absl::StatusOr<std::unique_ptr<cel::Source>> PrepareSourceImpl(
+      absl::string_view input, absl::string_view description) const = 0;
 };
 
 inline absl::StatusOr<std::unique_ptr<cel::Ast>> Parser::Parse(
@@ -134,6 +145,16 @@ inline absl::StatusOr<std::unique_ptr<cel::Ast>> Parser::Parse(
   return ParseImpl(source, issues);
 }
 
+inline absl::StatusOr<std::unique_ptr<cel::Source>> Parser::PrepareSource(
+    absl::string_view input, absl::string_view description) const {
+  return PrepareSourceImpl(input, description);
+}
+
+inline absl::StatusOr<std::unique_ptr<cel::Source>> Parser::PrepareSource(
+    absl::string_view input) const {
+  return PrepareSourceImpl(input, "<input>");
+}
+
 }  // namespace cel
 
 #endif  // THIRD_PARTY_CEL_CPP_PARSER_PARSER_INTERFACE_H_
diff --git a/parser/parser_test.cc b/parser/parser_test.cc
index c2fd36112..c04d819b2 100644
--- a/parser/parser_test.cc
+++ b/parser/parser_test.cc
@@ -2189,6 +2189,26 @@ TEST_P(ParserTest, MacroExpansionNodeLimitNotExceeded) {
   EXPECT_THAT(issues, testing::IsEmpty());
 }
 
+TEST_P(ParserTest, PrepareSourceForwardsCodepointLimit) {
+  auto builder = cel::NewParserBuilder(options_);
+  builder->GetOptions().expression_size_codepoint_limit = 10;
+  ASSERT_OK_AND_ASSIGN(auto parser, std::move(*builder).Build());
+
+  EXPECT_THAT(parser->PrepareSource("123456789012345", "test.cel"),
+              absl_testing::StatusIs(
+                  absl::StatusCode::kInvalidArgument,
+                  HasSubstr("expression is larger than codepoint limit 10")));
+
+  ASSERT_OK_AND_ASSIGN(auto source,
+                       parser->PrepareSource("1234567890", "test.cel"));
+  EXPECT_EQ(source->description(), "test.cel");
+  EXPECT_EQ(source->content().ToString(), "1234567890");
+
+  ASSERT_OK_AND_ASSIGN(auto source_default_desc,
+                       parser->PrepareSource("1234567890"));
+  EXPECT_EQ(source_default_desc->description(), "<input>");
+}
+
 std::string ExpressionTestName(
     const testing::TestParamInfo<std::tuple<TestInfo, bool>>& test_info) {
   const TestInfo& info = std::get<0>(test_info.param);