Index: lib/CodeGen/CoverageMappingGen.cpp
===================================================================
--- lib/CodeGen/CoverageMappingGen.cpp
+++ lib/CodeGen/CoverageMappingGen.cpp
@@ -92,6 +92,14 @@
   /// \brief The source mapping regions for this function.
   std::vector<SourceMappingRegion> SourceRegions;
 
+  /// \brief A set of regions which can be used as a filter.
+  ///
+  /// It is produced by emitExpansionRegions() and is used in
+  /// emitSourceRegions() to suppress producing code regions if
+  /// the same area is covered by expansion regions.
+  typedef llvm::SmallSet<std::pair<SourceLocation, SourceLocation>, 8>
+      SourceRegionFilter;
+
   CoverageMappingBuilder(CoverageMappingModuleGen &CVM, SourceManager &SM,
                          const LangOptions &LangOpts)
       : CVM(CVM), SM(SM), LangOpts(LangOpts) {}
@@ -249,7 +257,7 @@
 
   /// \brief Generate the coverage counter mapping regions from collected
   /// source regions.
-  void emitSourceRegions() {
+  void emitSourceRegions(const SourceRegionFilter &Filter) {
     for (const auto &Region : SourceRegions) {
       assert(Region.hasEndLoc() && "incomplete region");
 
@@ -269,6 +277,13 @@
       assert(SM.isWrittenInSameFile(LocStart, LocEnd) &&
              "region spans multiple files");
 
+      // Don't add code regions for the area covered by expansion regions.
+      // This not only suppresses redundant regions, but sometimes prevents
+      // creating regions with wrong counters if, for example, a statement's
+      // body ends at the end of a nested macro.
+      if (Filter.count(std::make_pair(LocStart, LocEnd)))
+        continue;
+
       // Find the spilling locations for the mapping region.
       unsigned LineStart = SM.getSpellingLineNumber(LocStart);
       unsigned ColumnStart = SM.getSpellingColumnNumber(LocStart);
@@ -283,7 +298,8 @@
   }
 
   /// \brief Generate expansion regions for each virtual file we've seen.
-  void emitExpansionRegions() {
+  SourceRegionFilter emitExpansionRegions() {
+    SourceRegionFilter Filter;
     for (const auto &FM : FileIDMapping) {
       SourceLocation ExpandedLoc = FM.second.second;
       SourceLocation ParentLoc = getIncludeOrExpansionLoc(ExpandedLoc);
@@ -299,6 +315,7 @@
       SourceLocation LocEnd = getPreciseTokenLocEnd(ParentLoc);
       assert(SM.isWrittenInSameFile(ParentLoc, LocEnd) &&
              "region spans multiple files");
+      Filter.insert(std::make_pair(ParentLoc, LocEnd));
 
       unsigned LineStart = SM.getSpellingLineNumber(ParentLoc);
       unsigned ColumnStart = SM.getSpellingColumnNumber(ParentLoc);
@@ -309,6 +326,7 @@
           *ParentFileID, *ExpandedFileID, LineStart, ColumnStart, LineEnd,
           ColumnEnd));
     }
+    return Filter;
   }
 };
 
@@ -350,7 +368,7 @@
   void write(llvm::raw_ostream &OS) {
     SmallVector<unsigned, 16> FileIDMapping;
     gatherFileIDs(FileIDMapping);
-    emitSourceRegions();
+    emitSourceRegions(SourceRegionFilter());
 
     if (MappingRegions.empty())
       return;
@@ -605,8 +623,8 @@
   void write(llvm::raw_ostream &OS) {
     llvm::SmallVector<unsigned, 8> VirtualFileMapping;
     gatherFileIDs(VirtualFileMapping);
-    emitSourceRegions();
-    emitExpansionRegions();
+    SourceRegionFilter Filter = emitExpansionRegions();
+    emitSourceRegions(Filter);
     gatherSkippedRegions();
 
     if (MappingRegions.empty())
Index: test/CoverageMapping/macroception.c
===================================================================
--- test/CoverageMapping/macroception.c
+++ test/CoverageMapping/macroception.c
@@ -11,7 +11,6 @@
 int main() M1
   return 0;
 }
-// CHECK-NEXT: File 1, 4:12 -> 4:14 = #0
 // CHECK-NEXT: Expansion,File 1, 4:12 -> 4:14 = #0
 // CHECK-NEXT: File 2, 3:12 -> 3:13 = #0
 
@@ -21,7 +20,6 @@
 void func2() {
   int x = 0;
 M11
-// CHECK-NEXT: File 1, 6:13 -> 6:16 = #0
 // CHECK-NEXT: Expansion,File 1, 6:13 -> 6:16 = #0
 // CHECK-NEXT: File 2, 5:13 -> 5:14 = #0
 
@@ -32,9 +30,7 @@
 void func3() M1
   int x = 0;
 M11
-// CHECK-NEXT: File 1, 4:12 -> 4:14 = #0
 // CHECK-NEXT: Expansion,File 1, 4:12 -> 4:14 = #0
-// CHECK-NEXT: File 2, 6:13 -> 6:16 = #0
 // CHECK-NEXT: Expansion,File 2, 6:13 -> 6:16 = #0
 // CHECK-NEXT: File 3, 3:12 -> 3:13 = #0
 // CHECK-NEXT: File 4, 5:13 -> 5:14 = #0
@@ -44,9 +40,7 @@
 // CHECK-NEXT: File 0, [[@LINE+2]]:16 -> [[@LINE+2]]:20 = #0
 // CHECK-NEXT: Expansion,File 0, [[@LINE+1]]:17 -> [[@LINE+1]]:20 = #0
 void func4() M1 M11
-// CHECK-NEXT: File 1, 4:12 -> 4:14 = #0
 // CHECK-NEXT: Expansion,File 1, 4:12 -> 4:14 = #0
-// CHECK-NEXT: File 2, 6:13 -> 6:16 = #0
 // CHECK-NEXT: Expansion,File 2, 6:13 -> 6:16 = #0
 // CHECK-NEXT: File 3, 3:12 -> 3:13 = #0
 // CHECK-NEXT: File 4, 5:13 -> 5:14 = #0
Index: test/CoverageMapping/macros.c
===================================================================
--- test/CoverageMapping/macros.c
+++ test/CoverageMapping/macros.c
@@ -3,6 +3,7 @@
 #define MACRO return; bar()
 #define MACRO_2 bar()
 #define MACRO_1 return; MACRO_2
+#define MACRO_3 MACRO_2
 
 void bar() {}
 
@@ -24,7 +25,6 @@
   i = 2;
 }
 // CHECK-NEXT: File 1, 5:17 -> 5:32 = #0
-// CHECK-NEXT: File 1, 5:25 -> 5:32 = 0
 // CHECK-NEXT: Expansion,File 1, 5:25 -> 5:32 = 0
 // CHECK-NEXT: File 2, 4:17 -> 4:22 = 0
 
@@ -47,6 +47,15 @@
 // CHECK-NEXT: File 1, 4:17 -> 4:22 = #2
 // CHECK-NOT: File 1
 
+// CHECK-NEXT: func5
+void func5() { // CHECK-NEXT: File 0, [[@LINE]]:14 -> [[@LINE+4]]:2 = #0
+  int i = 0;
+  if (i > 5) // CHECK-NEXT: File 0, [[@LINE]]:7 -> [[@LINE]]:12 = #0
+    MACRO_3; // CHECK-NEXT: Expansion,File 0, [[@LINE]]:5 -> [[@LINE]]:12 = #1
+}
+// CHECK-NEXT: Expansion,File 1, 6:17 -> 6:24 = #1
+// CHECK-NEXT: File 2, 4:17 -> 4:22 = #1
+
 int main(int argc, const char *argv[]) {
   func();
   func2();