diff --git a/lib/Frontend/DiagnosticRenderer.cpp b/lib/Frontend/DiagnosticRenderer.cpp
index aeab506b41..89d3867aad 100644
--- a/lib/Frontend/DiagnosticRenderer.cpp
+++ b/lib/Frontend/DiagnosticRenderer.cpp
@@ -306,56 +306,6 @@ void DiagnosticRenderer::emitModuleBuildStack(const SourceManager &SM) {
   }
 }
 
-// Find the common parent for the beginning and end of the range.
-static void findCommonParent(SourceLocation &Begin, SourceLocation &End,
-                             const SourceManager *SM) {
-  if (Begin.isInvalid() || End.isInvalid()) {
-    Begin = End = SourceLocation();
-    return;
-  }
-
-  FileID BeginFileID = SM->getFileID(Begin);
-  FileID EndFileID = SM->getFileID(End);
-
-  // First, crawl the expansion chain for the beginning of the range.
-  llvm::SmallDenseMap<FileID, SourceLocation> BeginLocsMap;
-  BeginLocsMap[BeginFileID] = Begin;
-  while (Begin.isMacroID() && BeginFileID != EndFileID) {
-    if (SM->isMacroArgExpansion(Begin)) {
-      Begin = SM->getImmediateSpellingLoc(Begin);
-      if (Begin.isMacroID())
-        continue;
-      Begin = SourceLocation();
-      BeginFileID = FileID();
-      break;
-    }
-    Begin = SM->getImmediateExpansionRange(Begin).first;
-    BeginFileID = SM->getFileID(Begin);
-    BeginLocsMap[BeginFileID] = Begin;
-  }
-
-  // Then, crawl the expansion chain for the end of the range.
-  if (BeginFileID != EndFileID) {
-    while (End.isMacroID() && !BeginLocsMap.count(EndFileID)) {
-      if (SM->isMacroArgExpansion(End)) {
-        End = SM->getImmediateSpellingLoc(End);
-        if (End.isMacroID())
-          continue;
-        End = SourceLocation();
-        EndFileID = FileID();
-        break;
-      }
-      End = SM->getImmediateExpansionRange(End).second;
-      EndFileID = SM->getFileID(End);
-    }
-    if (End.isMacroID()) {
-      Begin = BeginLocsMap[EndFileID];
-      BeginFileID = EndFileID;
-    }
-  }
-  assert(Begin.isValid() == End.isValid());
-}
-
 // Helper function to fix up source ranges.  It takes in an array of ranges,
 // and outputs an array of ranges where we want to draw the range highlighting
 // around the location specified by CaretLoc.
@@ -379,38 +329,40 @@ static void mapDiagnosticRanges(
     SourceLocation Begin = I->getBegin(), End = I->getEnd();
     bool IsTokenRange = I->isTokenRange();
 
-    // Compute the common parent; we can't highlight a range where
-    // the begin and end have different FileIDs.
-    findCommonParent(Begin, End, SM);
-
     FileID BeginFileID = SM->getFileID(Begin);
+    FileID EndFileID = SM->getFileID(End);
 
-    while (Begin.isMacroID() && BeginFileID != CaretLocFileID) {
-      if (SM->isMacroArgExpansion(Begin)) {
-        // We have a macro argument; take the spelling loc, which is
-        // a step closer to where the argument was written.
-        Begin = SM->getImmediateSpellingLoc(Begin);
-        End = SM->getImmediateSpellingLoc(End);
-        BeginFileID = SM->getFileID(Begin);
-        assert(BeginFileID == SM->getFileID(End));
-      } else {
-        // Take the next expansion in the expansion chain.
-        Begin = SM->getImmediateExpansionRange(Begin).first;
+    // Find the common parent for the beginning and end of the range.
+
+    // First, crawl the expansion chain for the beginning of the range.
+    llvm::SmallDenseMap<FileID, SourceLocation> BeginLocsMap;
+    while (Begin.isMacroID() && BeginFileID != EndFileID) {
+      BeginLocsMap[BeginFileID] = Begin;
+      Begin = SM->getImmediateExpansionRange(Begin).first;
+      BeginFileID = SM->getFileID(Begin);
+    }
+
+    // Then, crawl the expansion chain for the end of the range.
+    if (BeginFileID != EndFileID) {
+      while (End.isMacroID() && !BeginLocsMap.count(EndFileID)) {
         End = SM->getImmediateExpansionRange(End).second;
-
-        // Compute the common parent again; the beginning and end might
-        // come out of different macro expansions.
-        findCommonParent(Begin, End, SM);
-        BeginFileID = SM->getFileID(Begin);
+        EndFileID = SM->getFileID(End);
+      }
+      if (End.isMacroID()) {
+        Begin = BeginLocsMap[EndFileID];
+        BeginFileID = EndFileID;
       }
     }
 
-    // If this is the expansion of a macro argument, point the range at the
-    // use of the argument in the definition of the macro, not the expansion.
-    if (SM->isMacroArgExpansion(Begin)) {
-      assert(SM->isMacroArgExpansion(End));
-      Begin = End = SM->getImmediateExpansionRange(Begin).first;
-      IsTokenRange = true;
+    while (Begin.isMacroID() && BeginFileID != CaretLocFileID) {
+      if (SM->isMacroArgExpansion(Begin)) {
+        Begin = SM->getImmediateSpellingLoc(Begin);
+        End = SM->getImmediateSpellingLoc(End);
+      } else {
+        Begin = SM->getImmediateExpansionRange(Begin).first;
+        End = SM->getImmediateExpansionRange(End).second;
+      }
+      BeginFileID = SM->getFileID(Begin);
     }
 
     // Return the spelling location of the beginning and end of the range.
diff --git a/test/Misc/caret-diags-macros.c b/test/Misc/caret-diags-macros.c
index 8fcfeb070c..ce62425e78 100644
--- a/test/Misc/caret-diags-macros.c
+++ b/test/Misc/caret-diags-macros.c
@@ -181,10 +181,10 @@ void foo_aa()
 }
 // CHECK:         {{.*}}:180:21: warning: expression result unused
 // CHECK-NEXT:      iequals(__LINE__, BARC(4,3,2,6,8), 8);
-// CHECK-NEXT: {{^                    \^          ~}}
+// CHECK-NEXT: {{^                    \^~~~~~~~~~~~~~~}}
 // CHECK-NEXT:    {{.*}}:179:51: note: expanded from macro 'BARC'
 // CHECK-NEXT:    #define /* */ BARC(c, /* */b, a, ...) (a+b+/* */c + __VA_ARGS__ +0)
-// CHECK-NEXT: {{^                                                  \^}}
+// CHECK-NEXT: {{^                                       ~~~~~~~~~~ \^}}
 
 #define APPEND2(NUM, SUFF) -1 != NUM ## SUFF
 #define APPEND(NUM, SUFF) APPEND2(NUM, SUFF)
@@ -205,24 +205,3 @@ void foo_aa()
 // CHECK-NEXT:    {{.*}}:189:31: note: expanded from macro 'APPEND2'
 // CHECK-NEXT:    #define APPEND2(NUM, SUFF) -1 != NUM ## SUFF
 // CHECK-NEXT: {{^                           ~~ \^  ~~~~~~~~~~~}}
-
-
-unsigned long strlen_test(const char *s);
-#define __darwin_obsz(object) __builtin_object_size (object, 1)
-#define sprintf2(str, ...) \
-  __builtin___sprintf_chk (str, 0, __darwin_obsz(str), __VA_ARGS__)
-#define Cstrlen(a)  strlen_test(a)
-#define Csprintf    sprintf2
-void f(char* pMsgBuf, char* pKeepBuf) {
-Csprintf(pMsgBuf,"\nEnter minimum anagram length (2-%1d): ", Cstrlen(pKeepBuf));
-}
-// CHECK:         {{.*}}:217:62: warning: format specifies type 'int' but the argument has type 'unsigned long'
-// CHECK-NEXT:    Csprintf(pMsgBuf,"\nEnter minimum anagram length (2-%1d): ", Cstrlen(pKeepBuf));
-// CHECK-NEXT: {{^                                                    ~~~      \^~~~~~~~~~~~~~~~~}}
-// CHECK-NEXT: {{^                                                    %1ld}}
-// CHECK-NEXT:    {{.*}}:214:21: note: expanded from macro 'Cstrlen'
-// CHECK-NEXT:    #define Cstrlen(a)  strlen_test(a)
-// CHECK-NEXT: {{^                    \^}}
-// CHECK-NEXT:    {{.*}}:213:56: note: expanded from macro 'sprintf2'
-// CHECK-NEXT:      __builtin___sprintf_chk (str, 0, __darwin_obsz(str), __VA_ARGS__)
-// CHECK-NEXT: {{^                                                       \^}}