diff --git a/clang-tools-extra/clangd/ParsedAST.cpp b/clang-tools-extra/clangd/ParsedAST.cpp
index 81cfe8bb60b3e..3cf6671be9600 100644
--- a/clang-tools-extra/clangd/ParsedAST.cpp
+++ b/clang-tools-extra/clangd/ParsedAST.cpp
@@ -396,6 +396,15 @@ ParsedAST::build(llvm::StringRef Filename, const ParseInputs &Inputs,
     VFS = Preamble->StatCache->getConsumingFS(std::move(VFS));
 
   assert(CI);
+
+  if (CI->getFrontendOpts().Inputs.size() > 0) {
+    auto Lang = CI->getFrontendOpts().Inputs[0].getKind().getLanguage();
+    if (Lang == Language::Asm || Lang == Language::LLVM_IR) {
+      elog("Clangd does not support assembly or IR source files");
+      return std::nullopt;
+    }
+  }
+
   // Command-line parsing sets DisableFree to true by default, but we don't want
   // to leak memory in clangd.
   CI->getFrontendOpts().DisableFree = false;
diff --git a/clang-tools-extra/clangd/unittests/ParsedASTTests.cpp b/clang-tools-extra/clangd/unittests/ParsedASTTests.cpp
index b0d5bea1d3279..ec8132645f81f 100644
--- a/clang-tools-extra/clangd/unittests/ParsedASTTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ParsedASTTests.cpp
@@ -13,6 +13,7 @@
 
 #include "../../clang-tidy/ClangTidyCheck.h"
 #include "AST.h"
+#include "CompileCommands.h"
 #include "Compiler.h"
 #include "Config.h"
 #include "Diagnostics.h"
@@ -731,6 +732,37 @@ TEST(ParsedASTTest, DiscoversPragmaMarks) {
                                           pragmaTrivia(" End")));
 }
 
+TEST(ParsedASTTest, GracefulFailureOnAssemblyFile) {
+  std::string Filename = "TestTU.S";
+  std::string Code = R"S(
+main:
+    # test comment
+    bx lr
+  )S";
+
+  // The rest is a simplified version of TestTU::build().
+  // Don't call TestTU::build() itself because it would assert on
+  // failure to build an AST.
+  MockFS FS;
+  std::string FullFilename = testPath(Filename);
+  FS.Files[FullFilename] = Code;
+  ParseInputs Inputs;
+  auto &Argv = Inputs.CompileCommand.CommandLine;
+  Argv = {"clang"};
+  Argv.push_back(FullFilename);
+  Inputs.CompileCommand.Filename = FullFilename;
+  Inputs.CompileCommand.Directory = testRoot();
+  Inputs.Contents = Code;
+  Inputs.TFS = &FS;
+  StoreDiags Diags;
+  auto CI = buildCompilerInvocation(Inputs, Diags);
+  assert(CI && "Failed to build compilation invocation.");
+  auto AST = ParsedAST::build(FullFilename, Inputs, std::move(CI), {}, nullptr);
+
+  EXPECT_FALSE(AST.has_value())
+      << "Should not try to build AST for assembly source file";
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang