diff --git a/config/config.mk b/config/config.mk
index c937e2151fd..8aef9e5a714 100644
--- a/config/config.mk
+++ b/config/config.mk
@@ -219,8 +219,12 @@ endif
 ifdef MOZ_DEBUG_SYMBOLS
 OS_CXXFLAGS += -Zi -UDEBUG -DNDEBUG
 OS_CFLAGS += -Zi -UDEBUG -DNDEBUG
+ifdef HAVE_64BIT_OS
+OS_LDFLAGS += -DEBUG -OPT:REF,ICF
+else
 OS_LDFLAGS += -DEBUG -OPT:REF
 endif
+endif
 
 ifdef MOZ_QUANTIFY
 # -FIXED:NO is needed for Quantify to work, but it increases the size
@@ -239,7 +243,11 @@ endif
 #
 ifdef NS_TRACE_MALLOC
 MOZ_OPTIMIZE_FLAGS=-Zi -Od -UDEBUG -DNDEBUG
+ifdef HAVE_64BIT_OS
+OS_LDFLAGS = -DEBUG -PDB:NONE -OPT:REF,ICF
+else
 OS_LDFLAGS = -DEBUG -PDB:NONE -OPT:REF
+endif
 endif # NS_TRACE_MALLOC
 
 endif # MOZ_DEBUG
diff --git a/js/src/config/config.mk b/js/src/config/config.mk
index c937e2151fd..8aef9e5a714 100644
--- a/js/src/config/config.mk
+++ b/js/src/config/config.mk
@@ -219,8 +219,12 @@ endif
 ifdef MOZ_DEBUG_SYMBOLS
 OS_CXXFLAGS += -Zi -UDEBUG -DNDEBUG
 OS_CFLAGS += -Zi -UDEBUG -DNDEBUG
+ifdef HAVE_64BIT_OS
+OS_LDFLAGS += -DEBUG -OPT:REF,ICF
+else
 OS_LDFLAGS += -DEBUG -OPT:REF
 endif
+endif
 
 ifdef MOZ_QUANTIFY
 # -FIXED:NO is needed for Quantify to work, but it increases the size
@@ -239,7 +243,11 @@ endif
 #
 ifdef NS_TRACE_MALLOC
 MOZ_OPTIMIZE_FLAGS=-Zi -Od -UDEBUG -DNDEBUG
+ifdef HAVE_64BIT_OS
+OS_LDFLAGS = -DEBUG -PDB:NONE -OPT:REF,ICF
+else
 OS_LDFLAGS = -DEBUG -PDB:NONE -OPT:REF
+endif
 endif # NS_TRACE_MALLOC
 
 endif # MOZ_DEBUG