diff --git a/clif/backend/BUILD b/clif/backend/BUILD
index dac7d279..a643e48f 100644
--- a/clif/backend/BUILD
+++ b/clif/backend/BUILD
@@ -62,7 +62,6 @@ cc_library(
         "//clif/protos:ast_cc_proto",
         "@com_google_absl//absl/container:btree",
         "@com_google_absl//absl/log",
-        "@com_google_absl//absl/strings",
         "@com_google_googletest//:gtest_prod",
         "@llvm-project//clang:ast",
         "@llvm-project//clang:sema",
@@ -74,6 +73,7 @@ cc_library(
     name = "strutil",
     hdrs = ["strutil.h"],
     deps = [
+        "@com_google_absl//absl/strings",
         "@llvm-project//llvm:Support",
     ],
 )
diff --git a/clif/backend/code_builder.cc b/clif/backend/code_builder.cc
index 0f1e92bf..dc80e1cf 100644
--- a/clif/backend/code_builder.cc
+++ b/clif/backend/code_builder.cc
@@ -79,7 +79,6 @@
 #include <unordered_map>
 #include <vector>
 
-#include "absl/strings/str_cat.h"
 #include "clif/backend/strutil.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -391,7 +390,7 @@ const std::string& CodeBuilder::BuildCode(
     current_line_.pop_back();
     current_file_.pop_back();
   }
-  LLVM_DEBUG(llvm::dbgs() << absl::StrCat(*clif_ast));
+  LLVM_DEBUG(llvm::dbgs() << ProtoDebugString(*clif_ast));
   LLVM_DEBUG(llvm::dbgs() << code_);
   return code_;
 }
diff --git a/clif/backend/matcher.cc b/clif/backend/matcher.cc
index 31c5fc5b..d790e1ae 100644
--- a/clif/backend/matcher.cc
+++ b/clif/backend/matcher.cc
@@ -28,7 +28,6 @@
 
 #include "absl/container/btree_map.h"
 #include "absl/log/log.h"
-#include "absl/strings/str_cat.h"
 #include "clif/backend/strutil.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/Mangle.h"
@@ -352,7 +351,7 @@ bool ClifMatcher::CompileMatchAndSet(
     const std::string& input_file_name,
     const AST& clif_ast,
     AST* modified_clif_ast) {
-  LLVM_DEBUG(llvm::dbgs() << absl::StrCat(clif_ast));
+  LLVM_DEBUG(llvm::dbgs() << ProtoDebugString(clif_ast));
   *modified_clif_ast = clif_ast;
   modified_clif_ast->set_clif_matcher_argv0(clif_matcher_argv0_);
   modified_clif_ast->set_clif_matcher_version_stamp(kMatcherVersionStamp);
@@ -407,7 +406,7 @@ std::string ClifMatcher::GetQualTypeClifName(QualType qual_type) const {
 bool ClifMatcher::MatchAndSetAST(AST* clif_ast) {
   assert(ast_ != nullptr && "RunCompiler must be called prior to this.");
   int num_unmatched = MatchAndSetDecls(clif_ast->mutable_decls());
-  LLVM_DEBUG(llvm::dbgs() << "Matched proto:\n" << absl::StrCat(*clif_ast));
+  LLVM_DEBUG(llvm::dbgs() << "Matched proto:\n" << ProtoDebugString(*clif_ast));
   return num_unmatched == 0;
 }
 
@@ -1173,7 +1172,7 @@ bool ClifMatcher::MatchAndSetEnum(EnumDecl* enum_decl) {
       clif_name->set_native(result.GetFirst()->getNameAsString());
     }
   }
-  LLVM_DEBUG(llvm::dbgs() << absl::StrCat(*enum_decl));
+  LLVM_DEBUG(llvm::dbgs() << ProtoDebugString(*enum_decl));
   return true;
 }
 
@@ -2737,7 +2736,11 @@ const FunctionDecl* ClifMatcher::MatchAndSetFuncFromCandidates(
 
     if (auto method_decl = llvm::dyn_cast<clang::CXXMethodDecl>(clang_decl)) {
       func_decl->set_cpp_const_method(method_decl->isConst());
+#if PYCLIF_LLVM_VERSION_MAJOR >= 18  // llvm/llvm-project#78463
       func_decl->set_is_pure_virtual(method_decl->isPureVirtual());
+#else
+      func_decl->set_is_pure_virtual(method_decl->isPure());
+#endif
     }
 
     if (auto named_decl = llvm::dyn_cast<clang::NamedDecl>(clang_decl)) {
diff --git a/clif/backend/strutil.h b/clif/backend/strutil.h
index 4e5ccf04..dd6fca05 100644
--- a/clif/backend/strutil.h
+++ b/clif/backend/strutil.h
@@ -19,6 +19,7 @@
 #include <string>
 #include <vector>
 
+#include "absl/strings/str_cat.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
@@ -88,6 +89,11 @@ class NamespaceVector {
   ComponentsVector namespace_vector_;
 };
 
+template <typename ProtoType>
+std::string ProtoDebugString(const ProtoType& pb) {
+  return pb.DebugString();
+}
+
 }  // namespace clif
 
 #endif  // CLIF_BACKEND_STRUTIL_H_