diff --git a/common.mk b/common.mk
index ea5811ac..9913a778 100644
--- a/common.mk
+++ b/common.mk
@@ -16,10 +16,8 @@ HELP_COMPILATION_VARIABLES += \
 "   EXTRA_SIM_LDFLAGS         = additional LDFLAGS for building simulators" \
 "   EXTRA_SIM_SOURCES         = additional simulation sources needed for simulator" \
 "   EXTRA_SIM_REQS            = additional make requirements to build the simulator" \
-"   ENABLE_CUSTOM_FIRRTL_PASS = if set, enable custom firrtl passes (SFC lowers to LowFIRRTL & MFC converts to Verilog)" \
 "   ENABLE_YOSYS_FLOW         = if set, add compilation flags to enable the vlsi flow for yosys(tutorial flow)" \
 "   EXTRA_CHISEL_OPTIONS      = additional options to pass to the Chisel compiler" \
-"   EXTRA_BASE_FIRRTL_OPTIONS = additional options to pass to the Scala FIRRTL compiler" \
 "   MFC_BASE_LOWERING_OPTIONS = override lowering options to pass to the MLIR FIRRTL compiler" \
 "   ASPECTS                   = comma separated list of Chisel aspect flows to run (e.x. chipyard.upf.ChipTopUPFAspect)"
 
@@ -161,20 +159,11 @@ define mfc_extra_anno_contents
 	}
 ]
 endef
-define sfc_extra_low_transforms_anno_contents
-[
-	{
-		"class": "firrtl.stage.RunFirrtlTransformAnnotation",
-		"transform": "tapeout.transforms.ExtraLowTransforms"
-	}
-]
-endef
 export mfc_extra_anno_contents
 export sfc_extra_low_transforms_anno_contents
-$(EXTRA_ANNO_FILE) $(MFC_EXTRA_ANNO_FILE) $(SFC_EXTRA_ANNO_FILE) &: $(ANNO_FILE)
+$(FINAL_ANNO_FILE) $(MFC_EXTRA_ANNO_FILE) &: $(ANNO_FILE)
 	echo "$$mfc_extra_anno_contents" > $(MFC_EXTRA_ANNO_FILE)
-	echo "$$sfc_extra_low_transforms_anno_contents" > $(SFC_EXTRA_ANNO_FILE)
-	jq -s '[.[][]]' $(ANNO_FILE) $(MFC_EXTRA_ANNO_FILE) > $(EXTRA_ANNO_FILE)
+	jq -s '[.[][]]' $(ANNO_FILE) $(MFC_EXTRA_ANNO_FILE) > $(FINAL_ANNO_FILE)
 
 .PHONY: firrtl
 firrtl: $(FIRRTL_FILE) $(FINAL_ANNO_FILE)
@@ -192,30 +181,9 @@ SFC_MFC_TARGETS = \
 	$(MFC_BB_MODS_FILELIST) \
 	$(GEN_COLLATERAL_DIR)
 
-SFC_REPL_SEQ_MEM = --infer-rw --repl-seq-mem -c:$(MODEL):-o:$(SFC_SMEMS_CONF)
 MFC_BASE_LOWERING_OPTIONS ?= emittedLineLength=2048,noAlwaysComb,disallowLocalVariables,verifLabels,disallowPortDeclSharing,locationInfoStyle=wrapInAtSquareBracket
 
 # DOC include start: FirrtlCompiler
-# There are two possible cases for this step. In the first case, SFC
-# compiles Chisel to CHIRRTL, and MFC compiles CHIRRTL to Verilog. Otherwise,
-# when custom FIRRTL transforms are included or if a Fixed type is used within
-# the dut, SFC compiles Chisel to LowFIRRTL and MFC compiles it to Verilog.
-# Users can indicate to the Makefile of custom FIRRTL transforms by setting the
-# "ENABLE_CUSTOM_FIRRTL_PASS" variable.
-#
-# hack: lower to low firrtl if Fixed types are found
-# hack: when using dontTouch, io.cpu annotations are not removed by SFC,
-# hence we remove them manually by using jq before passing them to firtool
-
-$(SFC_LEVEL) $(EXTRA_FIRRTL_OPTIONS) &: $(FIRRTL_FILE)
-ifeq (,$(ENABLE_CUSTOM_FIRRTL_PASS))
-	echo $(if $(shell grep "Fixed<" $(FIRRTL_FILE)), low, none) > $(SFC_LEVEL)
-	echo "$(EXTRA_BASE_FIRRTL_OPTIONS)" $(if $(shell grep "Fixed<" $(FIRRTL_FILE)), "$(SFC_REPL_SEQ_MEM)",) > $(EXTRA_FIRRTL_OPTIONS)
-else
-	echo low > $(SFC_LEVEL)
-	echo "$(EXTRA_BASE_FIRRTL_OPTIONS)" "$(SFC_REPL_SEQ_MEM)" > $(EXTRA_FIRRTL_OPTIONS)
-endif
-
 $(MFC_LOWERING_OPTIONS):
 	mkdir -p $(dir $@)
 ifeq (,$(ENABLE_YOSYS_FLOW))
@@ -224,13 +192,7 @@ else
 	echo "$(MFC_BASE_LOWERING_OPTIONS),disallowPackedArrays" > $@
 endif
 
-$(FINAL_ANNO_FILE): $(EXTRA_ANNO_FILE) $(SFC_EXTRA_ANNO_FILE) $(SFC_LEVEL)
-	if [ $(shell cat $(SFC_LEVEL)) = low ]; then jq -s '[.[][]]' $(EXTRA_ANNO_FILE) $(SFC_EXTRA_ANNO_FILE) > $@; fi
-	if [ $(shell cat $(SFC_LEVEL)) = none ]; then cat $(EXTRA_ANNO_FILE) > $@; fi
-	touch $@
-
-$(SFC_MFC_TARGETS) &: private TMP_DIR := $(shell mktemp -d -t cy-XXXXXXXX)
-$(SFC_MFC_TARGETS) &: $(TAPEOUT_CLASSPATH_TARGETS) $(FIRRTL_FILE) $(FINAL_ANNO_FILE) $(SFC_LEVEL) $(EXTRA_FIRRTL_OPTIONS) $(MFC_LOWERING_OPTIONS)
+$(SFC_MFC_TARGETS) &: $(TAPEOUT_CLASSPATH_TARGETS) $(FIRRTL_FILE) $(FINAL_ANNO_FILE) $(MFC_LOWERING_OPTIONS)
 	rm -rf $(GEN_COLLATERAL_DIR)
 	$(call run_jar_scala_main,$(TAPEOUT_CLASSPATH),tapeout.transforms.GenerateModelStageMain,\
 		--no-dedup \
@@ -240,13 +202,9 @@ $(SFC_MFC_TARGETS) &: $(TAPEOUT_CLASSPATH_TARGETS) $(FIRRTL_FILE) $(FINAL_ANNO_F
 		--input-file $(FIRRTL_FILE) \
 		--annotation-file $(FINAL_ANNO_FILE) \
 		--log-level $(FIRRTL_LOGLEVEL) \
-		--allow-unrecognized-annotations \
-		-X $(shell cat $(SFC_LEVEL)) \
-		$(shell cat $(EXTRA_FIRRTL_OPTIONS)))
-	-mv $(SFC_FIRRTL_BASENAME).lo.fir $(SFC_FIRRTL_FILE) 2> /dev/null # Optionally change file type when SFC generates LowFIRRTL
-	@if [ $(shell cat $(SFC_LEVEL)) = low ]; then cat $(SFC_ANNO_FILE) | jq 'del(.[] | select(.target | test("io.cpu"))?)' > $(TMP_DIR)/unnec-anno-deleted.sfc.anno.json; fi
-	@if [ $(shell cat $(SFC_LEVEL)) = low ]; then cat $(TMP_DIR)/unnec-anno-deleted.sfc.anno.json | jq 'del(.[] | select(.class | test("SRAMAnnotation"))?)' > $(TMP_DIR)/unnec-anno-deleted2.sfc.anno.json; fi
-	@if [ $(shell cat $(SFC_LEVEL)) = low ]; then cat $(TMP_DIR)/unnec-anno-deleted2.sfc.anno.json > $(SFC_ANNO_FILE) && rm $(TMP_DIR)/unnec-anno-deleted.sfc.anno.json && rm $(TMP_DIR)/unnec-anno-deleted2.sfc.anno.json; fi
+		-X none \
+		--allow-unrecognized-annotations)
+	-mv $(SFC_FIRRTL_BASENAME).lo.fir $(SFC_FIRRTL_FILE)
 	firtool \
 		--format=fir \
 		--export-module-hierarchy \
@@ -262,7 +220,6 @@ $(SFC_MFC_TARGETS) &: $(TAPEOUT_CLASSPATH_TARGETS) $(FIRRTL_FILE) $(FINAL_ANNO_F
 		--split-verilog \
 		-o $(GEN_COLLATERAL_DIR) \
 		$(SFC_FIRRTL_FILE)
-	-mv $(SFC_SMEMS_CONF) $(MFC_SMEMS_CONF) 2> /dev/null
 	$(SED) -i 's/.*/& /' $(MFC_SMEMS_CONF) # need trailing space for SFC macrocompiler
 	touch $(MFC_BB_MODS_FILELIST) # if there are no BB's then the file might not be generated, instead always generate it
 # DOC include end: FirrtlCompiler
diff --git a/docs/Customization/Firrtl-Transforms.rst b/docs/Customization/Firrtl-Transforms.rst
index 7de7aadb..f7d565a7 100644
--- a/docs/Customization/Firrtl-Transforms.rst
+++ b/docs/Customization/Firrtl-Transforms.rst
@@ -8,12 +8,9 @@ modify Chisel-elaborated RTL.
 As mentioned in Section :ref:`Tools/FIRRTL:firrtl`, transforms are modifications that happen on the FIRRTL IR that can modify a circuit.
 Transforms are a powerful tool to take in the FIRRTL IR that is emitted from Chisel and run analysis or convert the circuit into a new form.
 
-The Scala FIRRTL Compiler and the MLIR FIRRTL Compiler
+The MLIR FIRRTL Compiler
 ------------------------------------------------------
-In Chipyard, two FIRRTL compilers work together to compile Chisel into Verilog. The Scala FIRRTL compiler (SFC) and the MLIR FIRRTL compiler (MFC).
-They are basically doing the same thing, except that MFC is written in C++ which makes compilation much faster (the generated Verilog will be different). In the default setting, the SFC will compile Chisel into CHIRRTL and MFC will
-compile CHIRRTL into Verilog (as of now, we are using SFC as a backup for cases when MFC doesn't work, e.g., when the design is using Fixed types). By setting the ``ENABLE_CUSTOM_FIRRTL_PASS`` env variable to a non-zero value,
-we can make the SFC compile Chisel into LowFIRRTL so that our custom FIRRTL passes are applied.
+In Chipyard, the LLVM-based MLIR FIRRTL compiler (CIRCT or MFC) compiles Chisel into Verilog.
 
 For more information on MLIR FIRRTL Compiler, please visit https://mlir.llvm.org/ and https://circt.llvm.org/.
 
diff --git a/variables.mk b/variables.mk
index 3bebdb1a..72b1bd2b 100644
--- a/variables.mk
+++ b/variables.mk
@@ -170,7 +170,6 @@ TAPEOUT_CLASSPATH_TARGETS ?= $(subst :, ,$(TAPEOUT_CLASSPATH))
 # chisel generated outputs
 FIRRTL_FILE ?= $(build_dir)/$(long_name).fir
 ANNO_FILE   ?= $(build_dir)/$(long_name).anno.json
-EXTRA_ANNO_FILE ?= $(build_dir)/$(long_name).extra.anno.json
 CHISEL_LOG_FILE ?= $(build_dir)/$(long_name).chisel.log
 
 # chisel anno modification output
@@ -180,7 +179,6 @@ FINAL_ANNO_FILE ?= $(build_dir)/$(long_name).appended.anno.json
 # scala firrtl compiler (sfc) outputs
 SFC_FIRRTL_BASENAME ?= $(build_dir)/$(long_name).sfc
 SFC_FIRRTL_FILE ?= $(SFC_FIRRTL_BASENAME).fir
-SFC_EXTRA_ANNO_FILE ?= $(build_dir)/$(long_name).extrasfc.anno.json
 SFC_ANNO_FILE ?= $(build_dir)/$(long_name).sfc.anno.json
 
 # firtool compiler outputs
@@ -195,7 +193,6 @@ MFC_TOP_SMEMS_JSON = $(GEN_COLLATERAL_DIR)/metadata/seq_mems.json
 MFC_MODEL_SMEMS_JSON = $(GEN_COLLATERAL_DIR)/metadata/tb_seq_mems.json
 
 # macrocompiler smems in/output
-SFC_SMEMS_CONF ?= $(build_dir)/$(long_name).sfc.mems.conf
 TOP_SMEMS_CONF ?= $(build_dir)/$(long_name).top.mems.conf
 TOP_SMEMS_FILE ?= $(GEN_COLLATERAL_DIR)/$(long_name).top.mems.v
 TOP_SMEMS_FIR  ?= $(build_dir)/$(long_name).top.mems.fir
@@ -228,8 +225,6 @@ sim_files              ?= $(build_dir)/sim_files.f
 # single file that contains all files needed for VCS or Verilator simulation (unique and without .h's)
 sim_common_files       ?= $(build_dir)/sim_files.common.f
 
-SFC_LEVEL ?= $(build_dir)/.sfc_level
-EXTRA_FIRRTL_OPTIONS ?= $(build_dir)/.extra_firrtl_options
 MFC_LOWERING_OPTIONS ?= $(build_dir)/.mfc_lowering_options
 
 #########################################################################################