diff --git a/include/sirit/sirit.h b/include/sirit/sirit.h
index f3925bb..d442191 100644
--- a/include/sirit/sirit.h
+++ b/include/sirit/sirit.h
@@ -12,6 +12,7 @@
 #include <optional>
 #include <span>
 #include <string>
+#include <functional>
 #include <string_view>
 #include <type_traits>
 #include <unordered_set>
@@ -52,6 +53,9 @@ public:
      */
     std::vector<std::uint32_t> Assemble() const;
 
+    /// Patches deferred phi nodes calling the passed function on each phi argument
+    void PatchDeferredPhi(const std::function<Id(std::size_t index)>& func);
+
     /// Adds a SPIR-V extension.
     void AddExtension(std::string extension_name);
 
@@ -87,15 +91,6 @@ public:
         AddExecutionMode(entry_point, mode, std::span<const Literal>({literals...}));
     }
 
-    /// Generate a new id for forward declarations
-    [[nodiscard]] Id ForwardDeclarationId();
-
-    /// Returns the current generator id, useful for self-referencing phi nodes
-    [[nodiscard]] Id CurrentId() const noexcept;
-
-    /// Assign a new id and return the old one, useful for defining forward declarations
-    Id ExchangeCurrentId(Id new_current_id);
-
     /**
      * Adds an existing label to the code
      * @param label Label to insert into code.
@@ -253,6 +248,12 @@ public:
      */
     Id OpPhi(Id result_type, std::span<const Id> operands);
 
+    /**
+     * The SSA phi function. This instruction will be revisited when patching phi nodes.
+     * @param operands An immutable span of block pairs
+     */
+    Id DeferredOpPhi(Id result_type, std::span<const Id> blocks);
+
     /// Declare a structured loop.
     Id OpLoopMerge(Id merge_block, Id continue_target, spv::LoopControlMask loop_control,
                    std::span<const Id> literals = {});
@@ -1236,6 +1237,7 @@ private:
     std::unique_ptr<Declarations> declarations;
     std::unique_ptr<Stream> global_variables;
     std::unique_ptr<Stream> code;
+    std::vector<std::uint32_t> deferred_phi_nodes;
 };
 
 } // namespace Sirit
diff --git a/src/instructions/flow.cpp b/src/instructions/flow.cpp
index e13caa9..e462dcb 100644
--- a/src/instructions/flow.cpp
+++ b/src/instructions/flow.cpp
@@ -18,6 +18,16 @@ Id Module::OpPhi(Id result_type, std::span<const Id> operands) {
     return *code << OpId{spv::Op::OpPhi, result_type} << operands << EndOp{};
 }
 
+Id Module::DeferredOpPhi(Id result_type, std::span<const Id> blocks) {
+    deferred_phi_nodes.push_back(code->LocalAddress());
+    code->Reserve(3 + blocks.size() * 2);
+    *code << OpId{spv::Op::OpPhi, result_type};
+    for (const Id block : blocks) {
+        *code << u32{0} << block;
+    }
+    return *code << EndOp{};
+}
+
 Id Module::OpLoopMerge(Id merge_block, Id continue_target, spv::LoopControlMask loop_control,
                        std::span<const Id> literals) {
     code->Reserve(4 + literals.size());
diff --git a/src/sirit.cpp b/src/sirit.cpp
index 22a4570..7075f23 100644
--- a/src/sirit.cpp
+++ b/src/sirit.cpp
@@ -68,6 +68,20 @@ std::vector<u32> Module::Assemble() const {
     return words;
 }
 
+void Module::PatchDeferredPhi(const std::function<Id(std::size_t index)>& func) {
+    for (const u32 phi_index : deferred_phi_nodes) {
+        const u32 first_word = code->Value(phi_index);
+        [[maybe_unused]] const spv::Op op = static_cast<spv::Op>(first_word & 0xffff);
+        assert(op == spv::Op::OpPhi);
+        const u32 num_words = first_word >> 16;
+        const u32 num_args = (num_words - 3) / 2;
+        u32 cursor = phi_index + 3;
+        for (u32 arg = 0; arg < num_args; ++arg, cursor += 2) {
+            code->SetValue(cursor, func(arg).value);
+        }
+    }
+}
+
 void Module::AddExtension(std::string extension_name) {
     extensions.insert(std::move(extension_name));
 }
@@ -95,19 +109,6 @@ void Module::AddExecutionMode(Id entry_point, spv::ExecutionMode mode,
     *execution_modes << spv::Op::OpExecutionMode << entry_point << mode << literals << EndOp{};
 }
 
-Id Module::ForwardDeclarationId() {
-    return Id{++bound};
-}
-
-Id Module::CurrentId() const noexcept {
-    return Id{bound + 1};
-}
-
-Id Module::ExchangeCurrentId(Id new_current_id) {
-    const std::uint32_t old_id = std::exchange(bound, new_current_id.value - 1);
-    return Id{old_id + 1};
-}
-
 Id Module::AddLabel(Id label) {
     assert(label.value != 0);
     code->Reserve(2);
diff --git a/src/stream.h b/src/stream.h
index ef7f2d2..ee3e7b8 100644
--- a/src/stream.h
+++ b/src/stream.h
@@ -40,7 +40,7 @@ struct OpId {
 
 struct EndOp {};
 
-constexpr size_t WordsInString(std::string_view string) {
+inline size_t WordsInString(std::string_view string) {
     return string.size() / sizeof(u32) + 1;
 }
 
@@ -76,6 +76,18 @@ public:
         return std::span(words.data(), insert_index);
     }
 
+    u32 LocalAddress() const noexcept {
+        return static_cast<u32>(words.size());
+    }
+
+    u32 Value(u32 index) const noexcept {
+        return words[index];
+    }
+
+    void SetValue(u32 index, u32 value) noexcept {
+        words[index] = value;
+    }
+
     Stream& operator<<(spv::Op op) {
         op_index = insert_index;
         words[insert_index++] = static_cast<u32>(op);