diff --git a/config/amd64/make_defs.mk b/config/amd64/make_defs.mk
index afea69558..668c7275e 100644
--- a/config/amd64/make_defs.mk
+++ b/config/amd64/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O2 -fomit-frame-pointer
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
@@ -74,7 +74,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/bulldozer/make_defs.mk b/config/bulldozer/make_defs.mk
index 15870c4cb..28328e4b7 100644
--- a/config/bulldozer/make_defs.mk
+++ b/config/bulldozer/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O2 -funroll-all-loops
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
@@ -74,7 +74,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/excavator/make_defs.mk b/config/excavator/make_defs.mk
index 45fff9690..82dcd8233 100644
--- a/config/excavator/make_defs.mk
+++ b/config/excavator/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O2 -fomit-frame-pointer
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
@@ -74,7 +74,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/generic/make_defs.mk b/config/generic/make_defs.mk
index d491d072e..93e4d5212 100644
--- a/config/generic/make_defs.mk
+++ b/config/generic/make_defs.mk
@@ -78,7 +78,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/haswell/make_defs.mk b/config/haswell/make_defs.mk
index 5d2f0a73b..41b61540a 100644
--- a/config/haswell/make_defs.mk
+++ b/config/haswell/make_defs.mk
@@ -78,7 +78,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/intel64/make_defs.mk b/config/intel64/make_defs.mk
index 442b81e3a..3a9cb8895 100644
--- a/config/intel64/make_defs.mk
+++ b/config/intel64/make_defs.mk
@@ -78,7 +78,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/knc/make_defs.mk b/config/knc/make_defs.mk
index 367b64b27..48b89159f 100644
--- a/config/knc/make_defs.mk
+++ b/config/knc/make_defs.mk
@@ -70,7 +70,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Override the default value for LDFLAGS.
 LDFLAGS        := -mmic
diff --git a/config/knl/make_defs.mk b/config/knl/make_defs.mk
index f4165f788..e239a2fdf 100644
--- a/config/knl/make_defs.mk
+++ b/config/knl/make_defs.mk
@@ -99,7 +99,7 @@ endif
 # Note: We use AVX2 for reference kernels instead of AVX-512.
 CROPTFLAGS     := $(CKOPTFLAGS)
 ifeq ($(CC_VENDOR),gcc)
-CRVECFLAGS     := -march=knl -mno-avx512f -mno-avx512pf -mno-avx512er -mno-avx512cd
+CRVECFLAGS     := -march=knl -mno-avx512f -mno-avx512pf -mno-avx512er -mno-avx512cd -funsafe-loop-optimizations
 else
 ifeq ($(CC_VENDOR),icc)
 CRVECFLAGS     := -xMIC-AVX512
diff --git a/config/penryn/make_defs.mk b/config/penryn/make_defs.mk
index 294dd616a..175c8d5bf 100644
--- a/config/penryn/make_defs.mk
+++ b/config/penryn/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O2 -fomit-frame-pointer
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
@@ -78,7 +78,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/piledriver/make_defs.mk b/config/piledriver/make_defs.mk
index 155b0c002..d5ebc1f14 100644
--- a/config/piledriver/make_defs.mk
+++ b/config/piledriver/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O2 -fomit-frame-pointer
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
@@ -74,7 +74,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/sandybridge/make_defs.mk b/config/sandybridge/make_defs.mk
index f0d694f8c..02fb4d641 100644
--- a/config/sandybridge/make_defs.mk
+++ b/config/sandybridge/make_defs.mk
@@ -78,7 +78,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/skx/make_defs.mk b/config/skx/make_defs.mk
index e9319e476..98c5ebd6f 100644
--- a/config/skx/make_defs.mk
+++ b/config/skx/make_defs.mk
@@ -89,7 +89,7 @@ endif
 # to overcome the AVX-512 frequency drop". (Issue #187)
 CROPTFLAGS     := $(CKOPTFLAGS)
 ifeq ($(CC_VENDOR),gcc)
-CRVECFLAGS     := -march=skylake-avx512 -mno-avx512f -mno-avx512vl -mno-avx512bw -mno-avx512dq -mno-avx512cd
+CRVECFLAGS     := -march=skylake-avx512 -mno-avx512f -mno-avx512vl -mno-avx512bw -mno-avx512dq -mno-avx512cd -funsafe-loop-optimizations
 else
 ifeq ($(CC_VENDOR),icc)
 CRVECFLAGS     := -xCORE-AVX2
diff --git a/config/steamroller/make_defs.mk b/config/steamroller/make_defs.mk
index 6c093d244..18c5c6461 100644
--- a/config/steamroller/make_defs.mk
+++ b/config/steamroller/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O2 -fomit-frame-pointer
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
@@ -74,7 +74,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/template/make_defs.mk b/config/template/make_defs.mk
index ff89757c7..35edf71a1 100644
--- a/config/template/make_defs.mk
+++ b/config/template/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O2
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
diff --git a/config/x86_64/make_defs.mk b/config/x86_64/make_defs.mk
index 375ea7dec..0c6c521bd 100644
--- a/config/x86_64/make_defs.mk
+++ b/config/x86_64/make_defs.mk
@@ -78,7 +78,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.
diff --git a/config/zen/make_defs.mk b/config/zen/make_defs.mk
index 40b07661b..5fdb7539f 100644
--- a/config/zen/make_defs.mk
+++ b/config/zen/make_defs.mk
@@ -57,7 +57,7 @@ endif
 ifeq ($(DEBUG_TYPE),noopt)
 COPTFLAGS      := -O0
 else
-COPTFLAGS      := -O3 -fomit-frame-pointer
+COPTFLAGS      := -O3
 endif
 
 # Flags specific to optimized kernels.
@@ -78,7 +78,11 @@ endif
 
 # Flags specific to reference kernels.
 CROPTFLAGS     := $(CKOPTFLAGS)
+ifeq ($(CC_VENDOR),gcc)
+CRVECFLAGS     := $(CKVECFLAGS) -funsafe-loop-optimizations
+else
 CRVECFLAGS     := $(CKVECFLAGS)
+endif
 
 # Store all of the variables here to new variables containing the
 # configuration name.