diff --git a/clang/include/clang/Lex/HeaderSearch.h b/clang/include/clang/Lex/HeaderSearch.h
--- a/clang/include/clang/Lex/HeaderSearch.h
+++ b/clang/include/clang/Lex/HeaderSearch.h
@@ -754,7 +754,8 @@
                                  const DirectoryEntry *Root,
                                  Module *RequestingModule,
                                  ModuleMap::KnownHeader *SuggestedModule,
-                                 bool IsSystemHeaderDir);
+                                 bool IsSystemHeaderDir,
+                                 StringRef FileName = "");
 
   /// Find and suggest a usable module for the given file, which is part of
   /// the specified framework.
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
@@ -415,7 +415,7 @@
   // If there is a module that corresponds to this header, suggest it.
   if (!findUsableModuleForHeader(
           &File->getFileEntry(), Dir ? Dir : File->getFileEntry().getDir(),
-          RequestingModule, SuggestedModule, IsSystemHeaderDir))
+          RequestingModule, SuggestedModule, IsSystemHeaderDir, FileName))
     return None;
 
   return *File;
@@ -1563,10 +1563,18 @@
 
 bool HeaderSearch::findUsableModuleForHeader(
     const FileEntry *File, const DirectoryEntry *Root, Module *RequestingModule,
-    ModuleMap::KnownHeader *SuggestedModule, bool IsSystemHeaderDir) {
+    ModuleMap::KnownHeader *SuggestedModule, bool IsSystemHeaderDir,
+    StringRef FileName) {
   if (File && needModuleLookup(RequestingModule, SuggestedModule)) {
     // If there is a module that corresponds to this header, suggest it.
-    hasModuleMap(File->getName(), Root, IsSystemHeaderDir);
+
+    // FIXME: File->getName() *should* be the same as FileName, but because
+    // of the VFS and various hacks in FileManager, that's not necessarily the
+    // case. We should update this to use FileEntryRef instead and either
+    // always give back the originally-requested path, or provide a way to get
+    // to get it.
+    hasModuleMap(FileName.empty() ? File->getName() : FileName, Root,
+                 IsSystemHeaderDir);
     return suggestModule(*this, File, RequestingModule, SuggestedModule);
   }
   return true;
diff --git a/clang/test/Modules/Inputs/all-product-headers.yaml b/clang/test/Modules/Inputs/all-product-headers.yaml
new file mode 100644
--- /dev/null
+++ b/clang/test/Modules/Inputs/all-product-headers.yaml
@@ -0,0 +1,33 @@
+{
+  'version': 0,
+  'case-sensitive': 'false',
+  'roots': [
+    {
+      'type': 'directory',
+      'name': "DUMMY_DIR/build/A.framework/PrivateHeaders"
+      'contents': [
+        {
+          'type': 'file',
+          'name': "A.h",
+          'external-contents': "DUMMY_DIR/sources/A.h"
+        }
+      ]
+    },
+    {
+      'type': 'directory',
+      'name': "DUMMY_DIR/build/A.framework/Modules"
+      'contents': [
+        {
+          'type': 'file',
+          'name': "module.modulemap",
+          'external-contents': "DUMMY_DIR/build/module.modulemap"
+        },
+        {
+          'type': 'file',
+          'name': "module.private.modulemap",
+          'external-contents': "DUMMY_DIR/build/module.private.modulemap"
+        }
+      ]
+    }
+  ]
+}
diff --git a/clang/test/Modules/modulemap-collision.m b/clang/test/Modules/modulemap-collision.m
new file mode 100644
--- /dev/null
+++ b/clang/test/Modules/modulemap-collision.m
@@ -0,0 +1,15 @@
+// REQUIRES: shell
+
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/sources %t/build
+// RUN: echo "// A.h" > %t/sources/A.h
+// RUN: echo "framework module A {}" > %t/sources/module.modulemap
+// RUN: echo "framework module A.Private { umbrella header \"A.h\" }" > %t/sources/module.private.modulemap
+// RUN: cp %t/sources/module.modulemap %t/build/module.modulemap
+// RUN: cp %t/sources/module.private.modulemap %t/build/module.private.modulemap
+
+// RUN: sed -e "s:DUMMY_DIR:%t:g" %S/Inputs/all-product-headers.yaml > %t/build/all-product-headers.yaml
+// RUN: %clang_cc1 -fsyntax-only -ivfsoverlay %t/build/all-product-headers.yaml -F%t/build -fmodules -fimplicit-module-maps -fmodules-cache-path=tmp -x objective-c %s -verify
+
+// expected-no-diagnostics
+#import <A/A.h>