diff --git a/clang-tools-extra/clangd/Compiler.cpp b/clang-tools-extra/clangd/Compiler.cpp
index 957d7c382125ef..04d48b08865d9d 100644
--- a/clang-tools-extra/clangd/Compiler.cpp
+++ b/clang-tools-extra/clangd/Compiler.cpp
@@ -41,8 +41,7 @@ void IgnoreDiagnostics::HandleDiagnostic(DiagnosticsEngine::Level DiagLevel,
 }
 
 std::unique_ptr<CompilerInvocation>
-buildCompilerInvocation(const ParseInputs &Inputs,
-                        clang::DiagnosticConsumer &D,
+buildCompilerInvocation(const ParseInputs &Inputs, clang::DiagnosticConsumer &D,
                         std::vector<std::string> *CC1Args) {
   std::vector<const char *> ArgStrs;
   for (const auto &S : Inputs.CompileCommand.CommandLine)
@@ -74,6 +73,15 @@ buildCompilerInvocation(const ParseInputs &Inputs,
   CI->getDependencyOutputOpts().HeaderIncludeOutputFile.clear();
   CI->getDependencyOutputOpts().DOTOutputFile.clear();
   CI->getDependencyOutputOpts().ModuleDependencyOutputDir.clear();
+
+  // Disable any pch generation/usage operations. Since serialized preamble
+  // format is unstable, using an incompatible one might result in unexpected
+  // behaviours, including crashes.
+  CI->getPreprocessorOpts().ImplicitPCHInclude.clear();
+  CI->getPreprocessorOpts().PrecompiledPreambleBytes = {0, false};
+  CI->getPreprocessorOpts().PCHThroughHeader.clear();
+  CI->getPreprocessorOpts().PCHWithHdrStop = false;
+  CI->getPreprocessorOpts().PCHWithHdrStopCreate = false;
   return CI;
 }
 
diff --git a/clang-tools-extra/clangd/unittests/CMakeLists.txt b/clang-tools-extra/clangd/unittests/CMakeLists.txt
index cccb3ce7308a14..a1f6af6747f4e1 100644
--- a/clang-tools-extra/clangd/unittests/CMakeLists.txt
+++ b/clang-tools-extra/clangd/unittests/CMakeLists.txt
@@ -34,6 +34,7 @@ add_unittest(ClangdUnitTests ClangdTests
   CodeCompletionStringsTests.cpp
   CollectMacrosTests.cpp
   CompileCommandsTests.cpp
+  CompilerTests.cpp
   DexTests.cpp
   DiagnosticsTests.cpp
   DraftStoreTests.cpp
diff --git a/clang-tools-extra/clangd/unittests/CompilerTests.cpp b/clang-tools-extra/clangd/unittests/CompilerTests.cpp
new file mode 100644
index 00000000000000..a12a7b9ce9af88
--- /dev/null
+++ b/clang-tools-extra/clangd/unittests/CompilerTests.cpp
@@ -0,0 +1,55 @@
+//===-- CompilerTests.cpp -------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Compiler.h"
+#include "TestTU.h"
+#include "clang/Lex/PreprocessorOptions.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace clangd {
+namespace {
+
+using testing::IsEmpty;
+
+TEST(BuildCompilerInvocation, DropsPCH) {
+  IgnoreDiagnostics Diags;
+  TestTU TU;
+  TU.AdditionalFiles["test.h.pch"] = "";
+
+  TU.ExtraArgs = {"-include-pch", "test.h.pch"};
+  EXPECT_THAT(buildCompilerInvocation(TU.inputs(), Diags)
+                  ->getPreprocessorOpts()
+                  .ImplicitPCHInclude,
+              IsEmpty());
+
+  // Transparent include translation
+  TU.ExtraArgs = {"-include", "test.h"};
+  EXPECT_THAT(buildCompilerInvocation(TU.inputs(), Diags)
+                  ->getPreprocessorOpts()
+                  .ImplicitPCHInclude,
+              IsEmpty());
+
+  // CL mode parsing.
+  TU.AdditionalFiles["test.pch"] = "";
+  TU.ExtraArgs = {"--driver-mode=cl"};
+  TU.ExtraArgs.push_back("/Yutest.h");
+  EXPECT_THAT(buildCompilerInvocation(TU.inputs(), Diags)
+                  ->getPreprocessorOpts()
+                  .ImplicitPCHInclude,
+              IsEmpty());
+  EXPECT_THAT(buildCompilerInvocation(TU.inputs(), Diags)
+                  ->getPreprocessorOpts()
+                  .PCHThroughHeader,
+              IsEmpty());
+}
+
+} // namespace
+} // namespace clangd
+} // namespace clang