diff --git a/nix/overlay.nix b/nix/overlay.nix
index 268b7a619..7a6be3ce3 100644
--- a/nix/overlay.nix
+++ b/nix/overlay.nix
@@ -14,7 +14,27 @@ rec {
 
   # Override "nixpkgs" circt with "nixpkgs-for-circt".
   # To update the "nixpkgs-for-circt" input, run `nix flake lock --update-input nixpkgs-for-circt`.
-  circt = self.inputs.nixpkgs-for-circt.legacyPackages."${final.system}".circt;
+  circt = self.inputs.nixpkgs-for-circt.legacyPackages."${final.system}".circt.overrideAttrs (old: rec {
+    version = "nightly";
+    src = final.fetchFromGitHub {
+      owner = "llvm";
+      repo = "circt";
+      rev = "1f6c29fb6465877d86c65d9ac2c6eeaa8f1e9044";
+      sha256 = "sha256-1tfClDKtVAp8j0+Aku5+2QTriqmsr3sjIReg7ekKZx0=";
+      fetchSubmodules = true;
+    };
+    preConfigure = ''
+      find ./test -name '*.mlir' -exec sed -i 's|/usr/bin/env|${final.coreutils}/bin/env|g' {} \;
+      substituteInPlace cmake/modules/GenVersionFile.cmake --replace "unknown git version" "nightly"
+    '';
+    patches = [
+      (final.fetchpatch {
+        url = "https://patch-diff.githubusercontent.com/raw/llvm/circt/pull/7210.diff";
+        sha256 = "sha256-eAWIcBgn+TDfZN/mi2IdoKNa9j6In864lTu88rFv2/o=";
+      })
+      ./pkgs/revert-llvm-bump.patch
+    ];
+  });
   espresso = final.callPackage ./pkgs/espresso.nix { };
   dramsim3 = final.callPackage ./pkgs/dramsim3.nix { };
   libspike = final.callPackage ./pkgs/libspike.nix { };
diff --git a/nix/pkgs/revert-llvm-bump.patch b/nix/pkgs/revert-llvm-bump.patch
new file mode 100644
index 000000000..f2fbd7cc8
--- /dev/null
+++ b/nix/pkgs/revert-llvm-bump.patch
@@ -0,0 +1,66 @@
+commit 0c621a4d56d10a12d54a4a163611ec1ddfb354b0
+Author: Jiuyang Liu <liu@jiuyang.me>
+Date:   Thu Jun 20 01:49:37 2024 +0800
+
+    Revert "Bump llvm (#7167)"
+    
+    This reverts commit f32a5a196cda8fcd11fbd95f2347d6ece31facb0.
+
+diff --git a/lib/Conversion/HandshakeToDC/HandshakeToDC.cpp b/lib/Conversion/HandshakeToDC/HandshakeToDC.cpp
+index cbc0171eb..8cd287872 100644
+--- a/lib/Conversion/HandshakeToDC/HandshakeToDC.cpp
++++ b/lib/Conversion/HandshakeToDC/HandshakeToDC.cpp
+@@ -605,7 +605,7 @@ public:
+       TypeConverter::SignatureConversion result(moduleRegion.getNumArguments());
+       (void)getTypeConverter()->convertSignatureArgs(
+           TypeRange(moduleRegion.getArgumentTypes()), result);
+-      rewriter.applySignatureConversion(hwModule.getBodyBlock(), result);
++      rewriter.applySignatureConversion(&moduleRegion, result);
+     }
+ 
+     rewriter.eraseOp(op);
+diff --git a/lib/Conversion/LLHDToLLVM/LLHDToLLVM.cpp b/lib/Conversion/LLHDToLLVM/LLHDToLLVM.cpp
+index 8d88faa44..ee85c1b77 100644
+--- a/lib/Conversion/LLHDToLLVM/LLHDToLLVM.cpp
++++ b/lib/Conversion/LLHDToLLVM/LLHDToLLVM.cpp
+@@ -623,7 +623,7 @@ struct EntityOpConversion : public ConvertToLLVMPattern {
+         std::array<Type, 3>({voidPtrTy, voidPtrTy, voidPtrTy}));
+     for (size_t i = 0, e = entityOp.getNumArguments(); i < e; ++i)
+       intermediate.addInputs(i, voidTy);
+-    rewriter.applySignatureConversion(entityOp.getBodyBlock(), intermediate,
++    rewriter.applySignatureConversion(&entityOp.getBody(), intermediate,
+                                       typeConverter);
+ 
+     OpBuilder bodyBuilder =
+@@ -646,7 +646,7 @@ struct EntityOpConversion : public ConvertToLLVMPattern {
+       final.remapInput(i + 3, gep.getResult());
+     }
+ 
+-    rewriter.applySignatureConversion(entityOp.getBodyBlock(), final,
++    rewriter.applySignatureConversion(&entityOp.getBody(), final,
+                                       typeConverter);
+ 
+     // Get the converted entity signature.
+@@ -718,7 +718,7 @@ struct ProcOpConversion : public ConvertToLLVMPattern {
+     intermediate.addInputs(procArgTys);
+     for (size_t i = 0, e = procOp.getNumArguments(); i < e; ++i)
+       intermediate.addInputs(i, voidTy);
+-    rewriter.applySignatureConversion(&procOp.getBlocks().front(), intermediate,
++    rewriter.applySignatureConversion(&procOp.getBody(), intermediate,
+                                       typeConverter);
+ 
+     // Get the final signature conversion.
+diff --git a/lib/Dialect/HW/ConversionPatterns.cpp b/lib/Dialect/HW/ConversionPatterns.cpp
+index 7f1452de0..3e1fecbbc 100644
+--- a/lib/Dialect/HW/ConversionPatterns.cpp
++++ b/lib/Dialect/HW/ConversionPatterns.cpp
+@@ -85,8 +85,7 @@ LogicalResult circt::doTypeConversion(Operation *op, ValueRange operands,
+             newRegion->getArgumentTypes(), result)))
+       return rewriter.notifyMatchFailure(op->getLoc(),
+                                          "type conversion failed");
+-    if (failed(rewriter.convertRegionTypes(newRegion, *typeConverter, &result)))
+-      return failure();
++    rewriter.applySignatureConversion(newRegion, result, typeConverter);
+   }
+   rewriter.finalizeOpModification(newOp);
+ 
\ No newline at end of file
diff --git a/nix/t1/_sources/generated.json b/nix/t1/_sources/generated.json
index f63d97782..96151f691 100644
--- a/nix/t1/_sources/generated.json
+++ b/nix/t1/_sources/generated.json
@@ -61,7 +61,7 @@
     },
     "chisel": {
         "cargoLocks": null,
-        "date": "2024-06-20",
+        "date": "2024-07-04",
         "extract": null,
         "name": "chisel",
         "passthru": null,
@@ -73,11 +73,11 @@
             "name": null,
             "owner": "chipsalliance",
             "repo": "chisel",
-            "rev": "0baa8fdf9b3688236d81797f5105bed45e06bdb5",
-            "sha256": "sha256-EQnlT4aB5XPa+fDTosVEHMjC/MhcC3I7cnfv0Ixzcx8=",
+            "rev": "b5fdc91dd2ec53afbb5c626835d8799baeffc4eb",
+            "sha256": "sha256-5McfF4y0Yrd32oelGYITAtcUjz+ddnubs2rCaa0iyTI=",
             "type": "github"
         },
-        "version": "0baa8fdf9b3688236d81797f5105bed45e06bdb5"
+        "version": "b5fdc91dd2ec53afbb5c626835d8799baeffc4eb"
     },
     "chisel-interface": {
         "cargoLocks": null,
diff --git a/nix/t1/_sources/generated.nix b/nix/t1/_sources/generated.nix
index 93b79d17a..78cecf1da 100644
--- a/nix/t1/_sources/generated.nix
+++ b/nix/t1/_sources/generated.nix
@@ -39,15 +39,15 @@
   };
   chisel = {
     pname = "chisel";
-    version = "0baa8fdf9b3688236d81797f5105bed45e06bdb5";
+    version = "b5fdc91dd2ec53afbb5c626835d8799baeffc4eb";
     src = fetchFromGitHub {
       owner = "chipsalliance";
       repo = "chisel";
-      rev = "0baa8fdf9b3688236d81797f5105bed45e06bdb5";
+      rev = "b5fdc91dd2ec53afbb5c626835d8799baeffc4eb";
       fetchSubmodules = false;
-      sha256 = "sha256-EQnlT4aB5XPa+fDTosVEHMjC/MhcC3I7cnfv0Ixzcx8=";
+      sha256 = "sha256-5McfF4y0Yrd32oelGYITAtcUjz+ddnubs2rCaa0iyTI=";
     };
-    date = "2024-06-20";
+    date = "2024-07-04";
   };
   chisel-interface = {
     pname = "chisel-interface";
diff --git a/nix/t1/nvfetcher.toml b/nix/t1/nvfetcher.toml
index c8f1f7886..6e061873f 100644
--- a/nix/t1/nvfetcher.toml
+++ b/nix/t1/nvfetcher.toml
@@ -35,7 +35,7 @@ fetch.github = "chipsalliance/rocket-chip-inclusive-cache"
 
 [chisel]
 src.git = "https://github.com/chipsalliance/chisel"
-src.branch = "main"
+src.branch = "sequencer/t1"
 fetch.github = "chipsalliance/chisel"
 
 [chisel-interface]