diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -481,6 +481,10 @@
 void Preprocessor::SuggestTypoedDirective(const Token &Tok,
                                           StringRef Directive,
                                           const SourceLocation &EndLoc) const {
+  // If this is a `.S` file, treat unknown # directives as non-preprocessor
+  // directives.
+  if (getLangOpts().AsmPreprocessor) return;
+
   std::vector<StringRef> Candidates = {
       "if", "ifdef", "ifndef", "elif", "else", "endif"
   };
diff --git a/clang/test/Preprocessor/suggest-typoed-directive.S b/clang/test/Preprocessor/suggest-typoed-directive.S
new file mode 100644
--- /dev/null
+++ b/clang/test/Preprocessor/suggest-typoed-directive.S
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -S %s -o %t
+
+// expected-no-diagnostics
+
+#ifdef UNDEFINED
+#id
+#ifd
+#ifde
+#elf
+#elsif
+#elseif
+#elfidef
+#elfindef
+#elfinndef
+#els
+#endi
+#endif
+
+#ifdef UNDEFINED
+# in in order to perform
+#endif
+
+#ifdef UNDEFINED
+#i
+#endif
+
+#if special_compiler
+#special_compiler_directive
+#endif