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
@@ -720,7 +720,8 @@
 }
 
 static bool isFrameworkStylePath(StringRef Path, bool &IsPrivateHeader,
-                                 SmallVectorImpl<char> &FrameworkName) {
+                                 SmallVectorImpl<char> &FrameworkName,
+                                 SmallVectorImpl<char> &IncludeSpelling) {
   using namespace llvm::sys;
   path::const_iterator I = path::begin(Path);
   path::const_iterator E = path::end(Path);
@@ -736,15 +737,22 @@
   // and some other variations among these lines.
   int FoundComp = 0;
   while (I != E) {
-    if (*I == "Headers")
+    if (*I == "Headers") {
       ++FoundComp;
-    if (I->endswith(".framework")) {
-      FrameworkName.append(I->begin(), I->end());
-      ++FoundComp;
-    }
-    if (*I == "PrivateHeaders") {
+    } else if (*I == "PrivateHeaders") {
       ++FoundComp;
       IsPrivateHeader = true;
+    } else if (I->endswith(".framework")) {
+      StringRef Name = I->drop_back(10); // Drop .framework
+      // Need to reset the strings and counter to support nested frameworks.
+      FrameworkName.clear();
+      FrameworkName.append(Name.begin(), Name.end());
+      IncludeSpelling.clear();
+      IncludeSpelling.append(Name.begin(), Name.end());
+      FoundComp = 1;
+    } else if (FoundComp >= 2) {
+      IncludeSpelling.push_back('/');
+      IncludeSpelling.append(I->begin(), I->end());
     }
     ++I;
   }
@@ -759,20 +767,24 @@
                          bool FoundByHeaderMap = false) {
   bool IsIncluderPrivateHeader = false;
   SmallString<128> FromFramework, ToFramework;
-  if (!isFrameworkStylePath(Includer, IsIncluderPrivateHeader, FromFramework))
+  SmallString<128> FromIncludeSpelling, ToIncludeSpelling;
+  if (!isFrameworkStylePath(Includer, IsIncluderPrivateHeader, FromFramework,
+                            FromIncludeSpelling))
     return;
   bool IsIncludeePrivateHeader = false;
-  bool IsIncludeeInFramework = isFrameworkStylePath(
-      IncludeFE->getName(), IsIncludeePrivateHeader, ToFramework);
+  bool IsIncludeeInFramework =
+      isFrameworkStylePath(IncludeFE->getName(), IsIncludeePrivateHeader,
+                           ToFramework, ToIncludeSpelling);
 
   if (!isAngled && !FoundByHeaderMap) {
     SmallString<128> NewInclude("<");
     if (IsIncludeeInFramework) {
-      NewInclude += ToFramework.str().drop_back(10); // drop .framework
-      NewInclude += "/";
+      NewInclude += ToIncludeSpelling;
+      NewInclude += ">";
+    } else {
+      NewInclude += IncludeFilename;
+      NewInclude += ">";
     }
-    NewInclude += IncludeFilename;
-    NewInclude += ">";
     Diags.Report(IncludeLoc, diag::warn_quoted_include_in_framework_header)
         << IncludeFilename
         << FixItHint::CreateReplacement(IncludeLoc, NewInclude);
@@ -1843,10 +1855,11 @@
   using namespace llvm::sys;
 
   unsigned BestPrefixLength = 0;
-  // Checks whether Dir and File shares a common prefix, if they do and that's
-  // the longest prefix we've seen so for it returns true and updates the
-  // BestPrefixLength accordingly.
-  auto CheckDir = [&](llvm::StringRef Dir) -> bool {
+  bool BestPrefixIsFramework = false;
+  // Checks whether `Dir` is a strict path prefix of `File`. If so and that's
+  // the longest prefix we've seen so for it, returns true and updates the
+  // `BestPrefixLength` accordingly.
+  auto CheckDir = [&](llvm::StringRef Dir, bool IsFramework) -> bool {
     llvm::SmallString<32> DirPath(Dir.begin(), Dir.end());
     if (!WorkingDir.empty() && !path::is_absolute(Dir))
       fs::make_absolute(WorkingDir, DirPath);
@@ -1870,6 +1883,7 @@
         unsigned PrefixLength = NI - path::begin(File);
         if (PrefixLength > BestPrefixLength) {
           BestPrefixLength = PrefixLength;
+          BestPrefixIsFramework = IsFramework;
           return true;
         }
         break;
@@ -1880,6 +1894,16 @@
           path::is_separator(NI->front()) && path::is_separator(DI->front()))
         continue;
 
+      // Special case Apple .sdk folders since the search path is typically a
+      // symlink like `iPhoneSimulator14.5.sdk` while the file is instead
+      // located in `iPhoneSimulator.sdk` (the real folder).
+      if (NI->endswith(".sdk") && DI->endswith(".sdk")) {
+        StringRef NBasename = path::stem(*NI);
+        StringRef DBasename = path::stem(*DI);
+        if (DBasename.startswith(NBasename))
+          continue;
+      }
+
       if (*NI != *DI)
         break;
     }
@@ -1887,18 +1911,22 @@
   };
 
   for (unsigned I = 0; I != SearchDirs.size(); ++I) {
-    // FIXME: Support this search within frameworks.
-    if (!SearchDirs[I].isNormalDir())
-      continue;
-
-    StringRef Dir = SearchDirs[I].getDir()->getName();
-    if (CheckDir(Dir) && IsSystem)
-      *IsSystem = BestPrefixLength ? I >= SystemDirIdx : false;
+    if (SearchDirs[I].isNormalDir()) {
+      StringRef Dir = SearchDirs[I].getDir()->getName();
+      if (CheckDir(Dir, /** IsFramework= */ false) && IsSystem)
+        *IsSystem = BestPrefixLength ? I >= SystemDirIdx : false;
+    } else if (SearchDirs[I].isFramework()) {
+      StringRef Dir = SearchDirs[I].getFrameworkDir()->getName();
+      if (CheckDir(Dir, /** IsFramework= */ true) && IsSystem)
+        *IsSystem = SearchDirs[I].isSystemHeaderDirectory();
+    }
   }
 
   // Try to shorten include path using TUs directory, if we couldn't find any
   // suitable prefix in include search paths.
-  if (!BestPrefixLength && CheckDir(path::parent_path(MainFile)) && IsSystem)
+  if (!BestPrefixLength &&
+      CheckDir(path::parent_path(MainFile), /** IsFramework= */ false) &&
+      IsSystem)
     *IsSystem = false;
 
   // Try resolving resulting filename via reverse search in header maps,
@@ -1912,8 +1940,39 @@
         SearchDirs[I].getHeaderMap()->reverseLookupFilename(Filename);
     if (!SpelledFilename.empty()) {
       Filename = SpelledFilename;
+      BestPrefixIsFramework = false;
       break;
     }
   }
+
+  // If the best prefix is a framework path, we need to compute the proper
+  // include spelling for the framework header.
+  bool IsPrivateHeader, MainIsPrivateHeader;
+  SmallString<128> FrameworkName, IncludeSpelling, MainFrameworkName,
+      MainIncludeSpelling;
+  if (BestPrefixIsFramework &&
+      isFrameworkStylePath(Filename, IsPrivateHeader, FrameworkName,
+                           IncludeSpelling)) {
+    // Prefer using `<UIKit/UIView.h>` only if the main file is in `UIKit`.
+    if (isFrameworkStylePath(MainFile, MainIsPrivateHeader, MainFrameworkName,
+                             MainIncludeSpelling) &&
+        MainFrameworkName == FrameworkName) {
+      Filename = IncludeSpelling;
+    } else {
+      // Prefer using `<UIKit/UIKit.h>` for non-`UIKit` main files.
+      //
+      // This assumes the framework has an umbrella header of the same name.
+      // There's not much more we can do without hitting the filesystem,
+      // especially if there's no modulemap.
+      IncludeSpelling.clear();
+      if (IsPrivateHeader)
+        llvm::sys::path::append(IncludeSpelling, FrameworkName,
+                                FrameworkName + "_Private.h");
+      else
+        llvm::sys::path::append(IncludeSpelling, FrameworkName,
+                                FrameworkName + ".h");
+      Filename = IncludeSpelling;
+    }
+  }
   return path::convert_to_slash(Filename);
 }