diff --git a/lib/IR/GCOV.cpp b/lib/IR/GCOV.cpp
index 8f060d2ac90..522716309a9 100644
--- a/lib/IR/GCOV.cpp
+++ b/lib/IR/GCOV.cpp
@@ -166,9 +166,11 @@ bool GCOVFunction::readGCNO(GCOVBuffer &Buff, GCOV::GCOVVersion Version) {
   // read line table.
   while (Buff.readLineTag()) {
     uint32_t LineTableLength;
+    // Read the length of this line table.
     if (!Buff.readInt(LineTableLength)) return false;
     uint32_t EndPos = Buff.getCursor() + LineTableLength*4;
     uint32_t BlockNo;
+    // Read the block number this table is associated with.
     if (!Buff.readInt(BlockNo)) return false;
     if (BlockNo >= BlockCount) {
       errs() << "Unexpected block number: " << BlockNo << " (in " << Name
@@ -176,24 +178,34 @@ bool GCOVFunction::readGCNO(GCOVBuffer &Buff, GCOV::GCOVVersion Version) {
       return false;
     }
     GCOVBlock &Block = *Blocks[BlockNo];
-    if (!Buff.readInt(Dummy)) return false; // flag
-    while (Buff.getCursor() != (EndPos - 4)) {
+    // Read the word that pads the beginning of the line table. This may be a
+    // flag of some sort, but seems to always be zero.
+    if (!Buff.readInt(Dummy)) return false;
+
+    // Line information starts here and continues up until the last word.
+    if (Buff.getCursor() != (EndPos - sizeof(uint32_t))) {
       StringRef F;
+      // Read the source file name.
       if (!Buff.readString(F)) return false;
       if (Filename != F) {
         errs() << "Multiple sources for a single basic block: " << Filename
                << " != " << F << " (in " << Name << ").\n";
         return false;
       }
-      if (Buff.getCursor() == (EndPos - 4)) break;
-      while (true) {
+      // Read lines up to, but not including, the null terminator.
+      while (Buff.getCursor() < (EndPos - 2 * sizeof(uint32_t))) {
         uint32_t Line;
         if (!Buff.readInt(Line)) return false;
-        if (!Line) break;
+        // Line 0 means this instruction was injected by the compiler. Skip it.
+        if (!Line) continue;
         Block.addLine(Line);
       }
+      // Read the null terminator.
+      if (!Buff.readInt(Dummy)) return false;
     }
-    if (!Buff.readInt(Dummy)) return false; // flag
+    // The last word is either a flag or padding, it isn't clear which. Skip
+    // over it.
+    if (!Buff.readInt(Dummy)) return false;
   }
   return true;
 }
diff --git a/test/tools/llvm-cov/Inputs/range_based_for.gcda b/test/tools/llvm-cov/Inputs/range_based_for.gcda
new file mode 100644
index 00000000000..df51888d48d
Binary files /dev/null and b/test/tools/llvm-cov/Inputs/range_based_for.gcda differ
diff --git a/test/tools/llvm-cov/Inputs/range_based_for.gcno b/test/tools/llvm-cov/Inputs/range_based_for.gcno
new file mode 100644
index 00000000000..5f30acf12f8
Binary files /dev/null and b/test/tools/llvm-cov/Inputs/range_based_for.gcno differ
diff --git a/test/tools/llvm-cov/lit.local.cfg b/test/tools/llvm-cov/lit.local.cfg
index f738810475f..dc1f6653796 100644
--- a/test/tools/llvm-cov/lit.local.cfg
+++ b/test/tools/llvm-cov/lit.local.cfg
@@ -1 +1 @@
-config.suffixes = ['.test', '.m']
+config.suffixes = ['.test', '.m', '.c', '.cpp']
diff --git a/test/tools/llvm-cov/range_based_for.cpp b/test/tools/llvm-cov/range_based_for.cpp
new file mode 100644
index 00000000000..61f60f6b0d6
--- /dev/null
+++ b/test/tools/llvm-cov/range_based_for.cpp
@@ -0,0 +1,29 @@
+// Make sure that compiler-added local variables (whose line number is zero)
+// don't crash llvm-cov.
+
+// We need shell for cd
+// REQUIRES: shell
+
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: cd %t
+// RUN: cp %s %p/Inputs/range_based_for.gc* .
+
+// RUN: llvm-cov range_based_for.cpp | FileCheck %s --check-prefix=STDOUT
+// STDOUT: File 'range_based_for.cpp'
+// STDOUT: Lines executed:100.00% of 5
+// STDOUT: range_based_for.cpp:creating 'range_based_for.cpp.gcov'
+
+// RUN: FileCheck %s --check-prefix=GCOV < %t/range_based_for.cpp.gcov
+// GCOV: -:    0:Runs:1
+// GCOV: -:    0:Programs:1
+
+int main(int argc, const char *argv[]) { // GCOV: 1:    [[@LINE]]:int main(
+  int V[] = {1, 2};                      // GCOV: 1:    [[@LINE]]:  int V[]
+  for (int &I : V) {                     // GCOV: 10:   [[@LINE]]:  for (
+  }                                      // GCOV: 2:    [[@LINE]]:  }
+  return 0;                              // GCOV: 1:    [[@LINE]]:  return
+}                                        // GCOV: -:    [[@LINE]]:}
+
+// llvm-cov doesn't work on big endian yet
+// XFAIL: powerpc64, s390x, mips-, mips64-, sparc