diff --git a/lib/CodeGen/CoverageMappingGen.cpp b/lib/CodeGen/CoverageMappingGen.cpp
index cf736a4..943c7e0 100644
--- a/lib/CodeGen/CoverageMappingGen.cpp
+++ b/lib/CodeGen/CoverageMappingGen.cpp
@@ -48,11 +48,16 @@
   /// Whether this region should be emitted after its parent is emitted.
   bool DeferRegion;
 
+  /// Whether this region is a gap region. The count from a gap region is set
+  /// as the line execution count if there are no other regions on the line.
+  bool GapRegion;
+
 public:
   SourceMappingRegion(Counter Count, Optional<SourceLocation> LocStart,
-                      Optional<SourceLocation> LocEnd, bool DeferRegion = false)
+                      Optional<SourceLocation> LocEnd, bool DeferRegion = false,
+                      bool GapRegion = false)
       : Count(Count), LocStart(LocStart), LocEnd(LocEnd),
-        DeferRegion(DeferRegion) {}
+        DeferRegion(DeferRegion), GapRegion(GapRegion) {}
 
   const Counter &getCounter() const { return Count; }
 
@@ -79,6 +84,10 @@
   bool isDeferred() const { return DeferRegion; }
 
   void setDeferred(bool Deferred) { DeferRegion = Deferred; }
+
+  bool isGap() const { return GapRegion; }
+
+  void setGap(bool Gap) { GapRegion = Gap; }
 };
 
 /// Spelling locations for the start and end of a source region.
@@ -322,9 +331,16 @@
       // Find the spelling locations for the mapping region.
       SpellingRegion SR{SM, LocStart, LocEnd};
       assert(SR.isInSourceOrder() && "region start and end out of order");
-      MappingRegions.push_back(CounterMappingRegion::makeRegion(
-          Region.getCounter(), *CovFileID, SR.LineStart, SR.ColumnStart,
-          SR.LineEnd, SR.ColumnEnd));
+
+      if (Region.isGap()) {
+        MappingRegions.push_back(CounterMappingRegion::makeGapRegion(
+            Region.getCounter(), *CovFileID, SR.LineStart, SR.ColumnStart,
+            SR.LineEnd, SR.ColumnEnd));
+      } else {
+        MappingRegions.push_back(CounterMappingRegion::makeRegion(
+            Region.getCounter(), *CovFileID, SR.LineStart, SR.ColumnStart,
+            SR.LineEnd, SR.ColumnEnd));
+      }
     }
   }
 
@@ -496,6 +512,7 @@
     if (!SpellingRegion(SM, DR.getStartLoc(), DeferredEndLoc).isInSourceOrder())
       return Index;
 
+    DR.setGap(true);
     DR.setCounter(Count);
     DR.setEndLoc(DeferredEndLoc);
     handleFileExit(DeferredEndLoc);
@@ -1112,6 +1129,9 @@
     case CounterMappingRegion::SkippedRegion:
       OS << "Skipped,";
       break;
+    case CounterMappingRegion::GapRegion:
+      OS << "Gap,";
+      break;
     }
 
     OS << "File " << R.FileID << ", " << R.LineStart << ":" << R.ColumnStart
diff --git a/test/CoverageMapping/deferred-region.cpp b/test/CoverageMapping/deferred-region.cpp
index 282b6a1..41b5e6b 100644
--- a/test/CoverageMapping/deferred-region.cpp
+++ b/test/CoverageMapping/deferred-region.cpp
@@ -7,7 +7,7 @@
 void foo(int x) {
   if (x == 0) {
     return;
-  } // CHECK: [[@LINE]]:4 -> [[@LINE+2]]:2 = (#0 - #1)
+  } // CHECK: Gap,File 0, [[@LINE]]:4 -> [[@LINE+2]]:2 = (#0 - #1)
 
 }
 
@@ -15,11 +15,11 @@
 void fooo(int x) {
   if (x == 0) {
     return;
-  } // CHECK: [[@LINE]]:4 -> [[@LINE+2]]:3 = (#0 - #1)
+  } // CHECK: Gap,File 0, [[@LINE]]:4 -> [[@LINE+2]]:3 = (#0 - #1)
 
   if (x == 1) {
     return;
-  } // CHECK: [[@LINE]]:4 -> [[@LINE+2]]:2 = ((#0 - #1) - #2)
+  } // CHECK: Gap,File 0, [[@LINE]]:4 -> [[@LINE+2]]:2 = ((#0 - #1) - #2)
 
 }
 
@@ -31,10 +31,10 @@
 // CHECK-LABEL: _Z3bari:
 void bar(int x) {
   IF (x)
-    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
+    return; // CHECK: Gap,File 0, [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
 
   IF (!x)
-    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = ((#0 - #1) - #2)
+    return; // CHECK: Gap,File 0, [[@LINE]]:11 -> [[@LINE+2]]:3 = ((#0 - #1) - #2)
 
   foo(x);
 }
@@ -69,34 +69,34 @@
   int i = 0;
 
   if (false)
-    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
+    return; // CHECK: Gap,File 0, [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
 
   if (false)
     i++;
 
   if (i + 100 > 0) { // CHECK: [[@LINE]]:20 -> [[@LINE+6]]:4 = #3
     if (false)       // CHECK: [[@LINE+1]]:7 -> [[@LINE+1]]:13 = #4
-      return;        // CHECK: [[@LINE]]:13 -> [[@LINE+2]]:5 = (#3 - #4)
+      return;        // CHECK: Gap,File 0, [[@LINE]]:13 -> [[@LINE+2]]:5 = (#3 - #4)
                      // CHECK: [[@LINE+1]]:5 -> [[@LINE+3]]:4 = (#3 - #4)
-    return;          // CHECK: [[@LINE]]:5 -> [[@LINE+4]]:3 = ((#0 - #1) - #3)
+    return;          // CHECK: Gap,File 0, [[@LINE]]:5 -> [[@LINE+4]]:3 = ((#0 - #1) - #3)
 
   }
 
   if (false)
-    return;
+    return; // CHECK: Gap,File 0, [[@LINE]]:11 -> [[@LINE+1]]:2
 }
 
 // CHECK-LABEL: _Z8for_loopv:
 void for_loop() {
   if (false)
-    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
+    return; // CHECK: Gap,File 0, [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
 
   for (int i = 0; i < 10; ++i) {
     if (i % 2 == 0)
-      continue; // CHECK: [[@LINE]]:15 -> [[@LINE+2]]:5 = (#2 - #3)
+      continue; // CHECK: Gap,File 0, [[@LINE]]:15 -> [[@LINE+2]]:5 = (#2 - #3)
 
     if (i % 5 == 0)
-      break; // CHECK: [[@LINE]]:12 -> [[@LINE+2]]:5 = ((#2 - #3) - #4)
+      break; // CHECK: Gap,File 0, [[@LINE]]:12 -> [[@LINE+2]]:5 = ((#2 - #3) - #4)
 
     int x = i; // CHECK: [[@LINE]]:5 -> [[@LINE+3]]:4 = ((#2 - #3) - #4)
     return; // CHECK-NOT: [[@LINE]]:11 -> [[@LINE+2]]
@@ -109,22 +109,22 @@
 // CHECK-LABEL: _Z10while_loopv:
 void while_loop() {
   if (false)
-    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
+    return; // CHECK: Gap,File 0, [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
 
   int x = 0;
   while (++x < 10) {
     if (x == 1)
-      continue; // CHECK: [[@LINE]]:15 -> [[@LINE+2]]:5 = (#2 - #3)
+      continue; // CHECK: Gap,File 0, [[@LINE]]:15 -> [[@LINE+2]]:5 = (#2 - #3)
 
     while (++x < 4) {
       if (x == 3)
-        break; // CHECK: [[@LINE]]:14 -> [[@LINE+2]]:7 = (#4 - #5)
+        break; // CHECK: Gap,File 0, [[@LINE]]:14 -> [[@LINE+2]]:7 = (#4 - #5)
 
       while (++x < 5) {}
     }
 
     if (x == 0)
-      throw Error(); // CHECK: [[@LINE]]:20 -> [[@LINE+2]]:5 = ((#2 - #3) - #7)
+      throw Error(); // CHECK: Gap,File 0, [[@LINE]]:20 -> [[@LINE+2]]:5 = ((#2 - #3) - #7)
 
     while (++x < 9) {
       if (x == 0)
@@ -137,12 +137,12 @@
 // CHECK-LABEL: _Z5gotosv:
 void gotos() {
   if (false)
-    goto out; // CHECK: [[@LINE]]:13 -> [[@LINE+2]]:3 = (#0 - #1)
+    goto out; // CHECK: Gap,File 0, [[@LINE]]:13 -> [[@LINE+2]]:3 = (#0 - #1)
 
   return; // CHECK: [[@LINE]]:3 -> [[@LINE+4]]:2 = (#0 - #1)
 
 out:
-	return; // CHECK: [[@LINE]]:8 -> [[@LINE+1]]:2 = 0
+	return; // CHECK: Gap,File 0, [[@LINE]]:8 -> [[@LINE+1]]:2 = 0
 }
 
 int main() {