diff --git a/gcc/gcc/Makefile.in b/gcc/gcc/Makefile.in
index ca68570..f6d4afa 100644
--- a/gcc/gcc/Makefile.in
+++ b/gcc/gcc/Makefile.in
@@ -2942,7 +2942,8 @@ ipa-struct-reorg.o: ipa-struct-reorg.c ipa-struct-reorg.h $(CONFIG_H) $(SYSTEM_H
 coverage.o : coverage.c $(GCOV_IO_H) $(CONFIG_H) $(SYSTEM_H) coretypes.h \
    $(TM_H) $(RTL_H) $(TREE_H) $(FLAGS_H) output.h $(REGS_H) $(EXPR_H) \
    $(FUNCTION_H) $(TOPLEV_H) $(GGC_H) langhooks.h $(COVERAGE_H) gt-coverage.h \
-   $(HASHTAB_H) tree-iterator.h $(CGRAPH_H) $(TREE_PASS_H) gcov-io.c $(TM_P_H)
+   $(HASHTAB_H) tree-iterator.h $(CGRAPH_H) $(TREE_PASS_H) gcov-io.c $(TM_P_H) \
+   $(DIAGNOSTIC_H) intl.h
 cselib.o : cselib.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
    $(REGS_H) hard-reg-set.h $(FLAGS_H) $(REAL_H) insn-config.h $(RECOG_H) \
    $(EMIT_RTL_H) $(TOPLEV_H) output.h $(FUNCTION_H) $(TREE_PASS_H) \
diff --git a/gcc/gcc/common.opt b/gcc/gcc/common.opt
index e62e3d5..806bd1f 100644
--- a/gcc/gcc/common.opt
+++ b/gcc/gcc/common.opt
@@ -249,8 +249,8 @@ Common Var(warn_unused_variable) Init(-1) Warning
 Warn when a variable is unused
 
 Wcoverage-mismatch
-Common RejectNegative Var(warn_coverage_mismatch) Warning
-Warn instead of error in case profiles in -fprofile-use do not match
+Common Var(warn_coverage_mismatch) Init(1) Warning
+Warn in case profiles in -fprofile-use do not match
 
 aux-info
 Common Separate
diff --git a/gcc/gcc/coverage.c b/gcc/gcc/coverage.c
index e04d22b..e279f03 100644
--- a/gcc/gcc/coverage.c
+++ b/gcc/gcc/coverage.c
@@ -46,6 +46,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-iterator.h"
 #include "cgraph.h"
 #include "tree-pass.h"
+#include "diagnostic.h"
+#include "intl.h"
 
 #include "gcov-io.c"
 
@@ -357,34 +359,33 @@ get_coverage_counts (unsigned counter, unsigned expected,
       || entry->summary.num != expected)
     {
       static int warned = 0;
+      bool warning_printed = false;
       tree id = DECL_ASSEMBLER_NAME (current_function_decl);
 
-      if (warn_coverage_mismatch)
-	warning (OPT_Wcoverage_mismatch, "coverage mismatch for function "
-		 "%qE while reading counter %qs", id, ctr_names[counter]);
-      else
-	error ("coverage mismatch for function %qE while reading counter %qs",
-	       id, ctr_names[counter]);
-
-      if (!inhibit_warnings)
+      warning_printed = 
+	warning_at (input_location, OPT_Wcoverage_mismatch, 
+		    "coverage mismatch for function "
+		    "%qE while reading counter %qs", id, ctr_names[counter]);
+      if (warning_printed)
 	{
 	  if (entry->checksum != checksum)
-	    inform (input_location, "checksum is %x instead of %x", entry->checksum, checksum);
+	    inform (input_location, "checksum is %x instead of %x",
+		    entry->checksum, checksum);
 	  else
 	    inform (input_location, "number of counters is %d instead of %d",
 		    entry->summary.num, expected);
-	}
-
-      if (warn_coverage_mismatch
-	  && !inhibit_warnings
-	  && !warned++)
-	{
-	  inform (input_location, "coverage mismatch ignored due to -Wcoverage-mismatch");
-	  inform (input_location, flag_guess_branch_prob
-		  ? "execution counts estimated"
-		  : "execution counts assumed to be zero");
-	  if (!flag_guess_branch_prob)
-	    inform (input_location, "this can result in poorly optimized code");
+	  
+	  if (!(errorcount || sorrycount)
+	      && !warned++)
+	    {
+	      inform (input_location, "coverage mismatch ignored");
+	      inform (input_location, flag_guess_branch_prob
+		      ? _("execution counts estimated")
+		      : _("execution counts assumed to be zero"));
+	      if (!flag_guess_branch_prob)
+		inform (input_location,
+			"this can result in poorly optimized code");
+	    }
 	}
 
       return NULL;
diff --git a/gcc/gcc/doc/invoke.texi b/gcc/gcc/doc/invoke.texi
index fefb0ab..492b82b 100644
--- a/gcc/gcc/doc/invoke.texi
+++ b/gcc/gcc/doc/invoke.texi
@@ -2746,12 +2746,13 @@ Warn if feedback profiles do not match when using the
 If a source file was changed between @option{-fprofile-gen} and
 @option{-fprofile-use}, the files with the profile feedback can fail
 to match the source file and GCC can not use the profile feedback
-information.  By default, GCC emits an error message in this case.
-The option @option{-Wcoverage-mismatch} emits a warning instead of an
-error.  GCC does not use appropriate feedback profiles, so using this
-option can result in poorly optimized code.  This option is useful
-only in the case of very minor changes such as bug fixes to an
-existing code-base.
+information.  By default, this warning is enabled and is treated as an
+error.  @option{-Wno-coverage-mismatch} can be used to disable the
+warning or @option{-Wno-error=coverage-mismatch} can be used to
+disable the error.  Disable the error for this warning can result in
+poorly optimized code, so disabling the error is useful only in the
+case of very minor changes such as bug fixes to an existing code-base.
+Completely disabling the warning is not recommended.
 
 @end table
 
diff --git a/gcc/gcc/opts.c b/gcc/gcc/opts.c
index 507b502..fd8a504 100644
--- a/gcc/gcc/opts.c
+++ b/gcc/gcc/opts.c
@@ -946,6 +946,9 @@ decode_options (unsigned int argc, const char **argv)
   else
     set_param_value ("min-crossjump-insns", initial_min_crossjump_insns);
 
+  /* Enable -Werror=coverage-mismatch by default */
+  enable_warning_as_error("coverage-mismatch", 1, lang_mask);
+
   if (first_time_p)
     {
       /* Initialize whether `char' is signed.  */
diff --git a/gcc/gcc/testsuite/gcc.dg/tree-prof/wcoverage-mismatch.c b/gcc/gcc/testsuite/gcc.dg/tree-prof/wcoverage-mismatch.c
index 74fe7f8..e423105 100644
--- a/gcc/gcc/testsuite/gcc.dg/tree-prof/wcoverage-mismatch.c
+++ b/gcc/gcc/testsuite/gcc.dg/tree-prof/wcoverage-mismatch.c
@@ -1,4 +1,4 @@
-/* { dg-options "-O2 -Wcoverage-mismatch -w" } */
+/* { dg-options "-O2 -Wno-coverage-mismatch" } */
 
 int __attribute__((noinline)) bar (void)
 {