diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -491,7 +491,8 @@
 
   IsInHeaderMap = true;
 
-  auto FixupSearchPath = [&]() {
+  auto FixupSearchPathAndFindUsableModule =
+      [&](auto File) -> OptionalFileEntryRef {
     if (SearchPath) {
       StringRef SearchPathRef(getName());
       SearchPath->clear();
@@ -501,6 +502,12 @@
       RelativePath->clear();
       RelativePath->append(Filename.begin(), Filename.end());
     }
+    if (!HS.findUsableModuleForHeader(
+            &File.getFileEntry(), File.getFileEntry().getDir(),
+            RequestingModule, SuggestedModule, isSystemHeaderDirectory())) {
+      return std::nullopt;
+    }
+    return File;
   };
 
   // Check if the headermap maps the filename to a framework include
@@ -513,8 +520,7 @@
   }
 
   if (auto Res = HS.getFileMgr().getOptionalFileRef(Dest, OpenFile)) {
-    FixupSearchPath();
-    return *Res;
+    return FixupSearchPathAndFindUsableModule(*Res);
   }
 
   // Header maps need to be marked as used whenever the filename matches.
diff --git a/clang/test/Modules/implicit-module-header-maps.cpp b/clang/test/Modules/implicit-module-header-maps.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Modules/implicit-module-header-maps.cpp
@@ -0,0 +1,53 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: cd %t
+//
+// RUN: %hmaptool write a.hmap.json hmap
+//
+// RUN: %clang -Rmodule-build -fmodules -fimplicit-modules -fimplicit-module-maps -fmodule-map-file=module.modulemap -fsyntax-only -I hmap -fmodules-cache-path=%t test.cpp
+//
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: cd %t
+//
+// RUN: sed -e "s|OUTPUTS_DIR|%t|g" -e "s#\\\\#/#g" b.hmap.json > hmap.json
+// RUN: %hmaptool write hmap.json hmap
+//
+// RUN: %clang -Rmodule-build -fmodules -fimplicit-modules -fimplicit-module-maps -fmodule-map-file=module.modulemap -fsyntax-only -I hmap -fmodules-cache-path=%t test.cpp
+
+//--- After/Mapping.h
+#ifdef FOO
+#error foo
+#endif
+
+//--- a.hmap.json
+{
+  "mappings" :
+    {
+     "Before/Mapping.h" : "After/Mapping.h",
+     "After/Mapping.h" : "After/Mapping.h"
+    }
+}
+
+//--- b.hmap.json
+{
+  "mappings" :
+    {
+     "Before/Mapping.h" : "OUTPUTS_DIR/After/Mapping.h"
+    }
+}
+
+//--- module.modulemap
+module a {
+  header "After/Mapping.h"
+}
+
+
+//--- test.cpp
+#define FOO
+// This include will fail if:
+// 1) modules are't used, as the `FOO` define will propagate into the included
+//    header and trip a `#error`, or
+// 2) header maps aren't usesd, as the header name doesn't exist and relies on
+//    the header map to remap it to the real header.
+#include "Before/Mapping.h"