diff --git a/build/unix/elfhack/Makefile.in b/build/unix/elfhack/Makefile.in
index 54d7d7c7219..18cfccfaa6a 100644
--- a/build/unix/elfhack/Makefile.in
+++ b/build/unix/elfhack/Makefile.in
@@ -47,7 +47,6 @@ INTERNAL_TOOLS = 1
 
 HOST_PROGRAM = elfhack
 NO_DIST_INSTALL = 1
-override MOZ_PROFILE_GENERATE =
 
 VPATH += $(topsrcdir)/build
 
diff --git a/config/config.mk b/config/config.mk
index 27a10317088..669c21277f1 100644
--- a/config/config.mk
+++ b/config/config.mk
@@ -782,15 +782,3 @@ EXPAND_MKSHLIB = $(EXPAND_LIBS_EXEC) --uselist -- $(MKSHLIB)
 ifdef STDCXX_COMPAT
 CHECK_STDCXX = objdump -p $(1) | grep -e 'GLIBCXX_3\.4\.\(9\|[1-9][0-9]\)' > /dev/null && echo "TEST-UNEXPECTED-FAIL | | We don't want these libstdc++ symbols to be used:" && objdump -T $(1) | grep -e 'GLIBCXX_3\.4\.\(9\|[1-9][0-9]\)' && exit 1 || exit 0
 endif
-
-# PGO builds with GCC build objects with instrumentation in a first pass,
-# then objects optimized, without instrumentation, in a second pass. If
-# we overwrite the ojects from the first pass with those from the second,
-# we end up not getting instrumentation data for better optimization on
-# incremental builds. As a consequence, we use a different object suffix
-# for the first pass.
-ifdef MOZ_PROFILE_GENERATE
-ifdef GNU_CC
-OBJ_SUFFIX := i_o
-endif
-endif
diff --git a/config/expandlibs_exec.py b/config/expandlibs_exec.py
index fcea5c7d277..20cbac679ef 100644
--- a/config/expandlibs_exec.py
+++ b/config/expandlibs_exec.py
@@ -93,7 +93,7 @@ class ExpandArgsMore(ExpandArgs):
                     subprocess.call(ar_extract + [os.path.abspath(arg)], cwd=tmp)
                     objs = []
                     for root, dirs, files in os.walk(tmp):
-                        objs += [relativize(os.path.join(root, f)) for f in files if os.path.splitext(f)[1] in [conf.OBJ_SUFFIX, '.i_o']]
+                        objs += [relativize(os.path.join(root, f)) for f in files if os.path.splitext(f)[1] == conf.OBJ_SUFFIX]
                     newlist += objs
                 else:
                     newlist += [arg]
diff --git a/config/expandlibs_gen.py b/config/expandlibs_gen.py
index 437687b7d26..beaaf2e74b7 100644
--- a/config/expandlibs_gen.py
+++ b/config/expandlibs_gen.py
@@ -46,7 +46,7 @@ from expandlibs import LibDescriptor
 def generate(args):
     desc = LibDescriptor()
     for arg in args:
-        if os.path.splitext(arg)[1] in [conf.OBJ_SUFFIX, '.i_o']:
+        if os.path.splitext(arg)[1] == conf.OBJ_SUFFIX:
             desc['OBJS'].append(os.path.abspath(arg))
         elif os.path.splitext(arg)[1] == conf.LIB_SUFFIX and \
              (os.path.exists(arg) or os.path.exists(arg + conf.LIBS_DESC_SUFFIX)):
diff --git a/config/rules.mk b/config/rules.mk
index b75ad78bf3e..166a00b4ee3 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -390,7 +390,7 @@ endif
 ALL_TRASH = \
 	$(GARBAGE) $(TARGETS) $(OBJS) $(PROGOBJS) LOGS TAGS a.out \
 	$(filter-out $(ASFILES),$(OBJS:.$(OBJ_SUFFIX)=.s)) $(OBJS:.$(OBJ_SUFFIX)=.ii) \
-	$(OBJS:.$(OBJ_SUFFIX)=.i) $(OBJS:.$(OBJ_SUFFIX)=.i_o) \
+	$(OBJS:.$(OBJ_SUFFIX)=.i) \
 	$(HOST_PROGOBJS) $(HOST_OBJS) $(IMPORT_LIBRARY) $(DEF_FILE)\
 	$(EXE_DEF_FILE) so_locations _gen _stubs $(wildcard *.res) $(wildcard *.RES) \
 	$(wildcard *.pdb) $(CODFILE) $(MAPFILE) $(IMPORT_LIBRARY) \
@@ -914,15 +914,6 @@ ifdef GNU_CC
 endif
 endif
 endif
-
-ifneq (,$(MOZ_PROFILE_GENERATE)$(MOZ_PROFILE_USE))
-ifdef GNU_CC
-# Force rebuilding libraries and programs in both passes because each
-# pass uses different object files.
-$(PROGRAM) $(SHARED_LIBRARY) $(LIBRARY): FORCE
-endif
-endif
-
 endif # NO_PROFILE_GUIDED_OPTIMIZE
 
 ##############################################
diff --git a/js/src/config/config.mk b/js/src/config/config.mk
index 27a10317088..669c21277f1 100644
--- a/js/src/config/config.mk
+++ b/js/src/config/config.mk
@@ -782,15 +782,3 @@ EXPAND_MKSHLIB = $(EXPAND_LIBS_EXEC) --uselist -- $(MKSHLIB)
 ifdef STDCXX_COMPAT
 CHECK_STDCXX = objdump -p $(1) | grep -e 'GLIBCXX_3\.4\.\(9\|[1-9][0-9]\)' > /dev/null && echo "TEST-UNEXPECTED-FAIL | | We don't want these libstdc++ symbols to be used:" && objdump -T $(1) | grep -e 'GLIBCXX_3\.4\.\(9\|[1-9][0-9]\)' && exit 1 || exit 0
 endif
-
-# PGO builds with GCC build objects with instrumentation in a first pass,
-# then objects optimized, without instrumentation, in a second pass. If
-# we overwrite the ojects from the first pass with those from the second,
-# we end up not getting instrumentation data for better optimization on
-# incremental builds. As a consequence, we use a different object suffix
-# for the first pass.
-ifdef MOZ_PROFILE_GENERATE
-ifdef GNU_CC
-OBJ_SUFFIX := i_o
-endif
-endif
diff --git a/js/src/config/expandlibs_exec.py b/js/src/config/expandlibs_exec.py
index fcea5c7d277..20cbac679ef 100644
--- a/js/src/config/expandlibs_exec.py
+++ b/js/src/config/expandlibs_exec.py
@@ -93,7 +93,7 @@ class ExpandArgsMore(ExpandArgs):
                     subprocess.call(ar_extract + [os.path.abspath(arg)], cwd=tmp)
                     objs = []
                     for root, dirs, files in os.walk(tmp):
-                        objs += [relativize(os.path.join(root, f)) for f in files if os.path.splitext(f)[1] in [conf.OBJ_SUFFIX, '.i_o']]
+                        objs += [relativize(os.path.join(root, f)) for f in files if os.path.splitext(f)[1] == conf.OBJ_SUFFIX]
                     newlist += objs
                 else:
                     newlist += [arg]
diff --git a/js/src/config/expandlibs_gen.py b/js/src/config/expandlibs_gen.py
index 437687b7d26..beaaf2e74b7 100644
--- a/js/src/config/expandlibs_gen.py
+++ b/js/src/config/expandlibs_gen.py
@@ -46,7 +46,7 @@ from expandlibs import LibDescriptor
 def generate(args):
     desc = LibDescriptor()
     for arg in args:
-        if os.path.splitext(arg)[1] in [conf.OBJ_SUFFIX, '.i_o']:
+        if os.path.splitext(arg)[1] == conf.OBJ_SUFFIX:
             desc['OBJS'].append(os.path.abspath(arg))
         elif os.path.splitext(arg)[1] == conf.LIB_SUFFIX and \
              (os.path.exists(arg) or os.path.exists(arg + conf.LIBS_DESC_SUFFIX)):
diff --git a/js/src/config/rules.mk b/js/src/config/rules.mk
index b75ad78bf3e..166a00b4ee3 100644
--- a/js/src/config/rules.mk
+++ b/js/src/config/rules.mk
@@ -390,7 +390,7 @@ endif
 ALL_TRASH = \
 	$(GARBAGE) $(TARGETS) $(OBJS) $(PROGOBJS) LOGS TAGS a.out \
 	$(filter-out $(ASFILES),$(OBJS:.$(OBJ_SUFFIX)=.s)) $(OBJS:.$(OBJ_SUFFIX)=.ii) \
-	$(OBJS:.$(OBJ_SUFFIX)=.i) $(OBJS:.$(OBJ_SUFFIX)=.i_o) \
+	$(OBJS:.$(OBJ_SUFFIX)=.i) \
 	$(HOST_PROGOBJS) $(HOST_OBJS) $(IMPORT_LIBRARY) $(DEF_FILE)\
 	$(EXE_DEF_FILE) so_locations _gen _stubs $(wildcard *.res) $(wildcard *.RES) \
 	$(wildcard *.pdb) $(CODFILE) $(MAPFILE) $(IMPORT_LIBRARY) \
@@ -914,15 +914,6 @@ ifdef GNU_CC
 endif
 endif
 endif
-
-ifneq (,$(MOZ_PROFILE_GENERATE)$(MOZ_PROFILE_USE))
-ifdef GNU_CC
-# Force rebuilding libraries and programs in both passes because each
-# pass uses different object files.
-$(PROGRAM) $(SHARED_LIBRARY) $(LIBRARY): FORCE
-endif
-endif
-
 endif # NO_PROFILE_GUIDED_OPTIMIZE
 
 ##############################################