diff --git a/NEWS.md b/NEWS.md
index edd474671f359..f9433e746f638 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -84,6 +84,11 @@ New library functions
   efficiently ([#35816]).
 * New function `addenv` for adding environment mappings into a `Cmd` object, returning the new `Cmd` object.
 * New function `insorted` for determining whether an element is in a sorted collection or not ([#37490]).
+* New function `isdebug` for checking if julia is running in debug mode.
+  Packages use different precompile caches in debug and non-debug mode thus it
+  safe to use this function for compile time decisions. Also, note that
+  `@assert` now is a no-op unless `isdebug()` is true. Debug mode is activated
+  with the `-g2` flag.
 
 New library features
 --------------------
@@ -124,6 +129,8 @@ Standard library changes
 * The `Pkg.Artifacts` module has been imported as a separate standard library.  It is still available as
   `Pkg.Artifacts`, however starting from Julia v1.6+, packages may import simply `Artifacts` without importing
   all of `Pkg` alongside. ([#37320])
+* The `@assert` macro is now only active when julia is started with a debug
+  level of 2 (`julia -g2`).
 
 #### LinearAlgebra
 
diff --git a/base/Base.jl b/base/Base.jl
index 207b571f30e16..a8f22a9922efc 100644
--- a/base/Base.jl
+++ b/base/Base.jl
@@ -66,6 +66,9 @@ time_ns() = ccall(:jl_hrtime, UInt64, ())
 
 start_base_include = time_ns()
 
+julia_debug = true
+isdebug() = julia_debug::Bool
+
 ## Load essential files and libraries
 include("essentials.jl")
 include("ctypes.jl")
@@ -396,6 +399,7 @@ in_sysimage(pkgid::PkgId) = pkgid in _sysimage_modules
 
 if is_primary_base_module
 function __init__()
+    global julia_debug = Base.JLOptions().debug_level >= 2
     # try to ensuremake sure OpenBLAS does not set CPU affinity (#1070, #9639)
     if !haskey(ENV, "OPENBLAS_MAIN_FREE") && !haskey(ENV, "GOTOBLAS_MAIN_FREE")
         ENV["OPENBLAS_MAIN_FREE"] = "1"
diff --git a/base/error.jl b/base/error.jl
index 16b66af68be12..49cd7869945ec 100644
--- a/base/error.jl
+++ b/base/error.jl
@@ -183,21 +183,25 @@ windowserror(p, b::Bool; extrainfo=nothing) = b ? windowserror(p, extrainfo=extr
 windowserror(p, code::UInt32=Libc.GetLastError(); extrainfo=nothing) = throw(Main.Base.SystemError(string(p), 0, WindowsErrorInfo(code, extrainfo)))
 
 
-## assertion macro ##
+## assertion and ifdebug macros ##
+
+"""
+    @ifdebug expr
+
+Equivalent to `@static if isdebug()`
+"""
+macro ifdebug(expr)
+    isdefined(@__MODULE__, :isdebug) && !(isdebug()) && return nothing
+    return :(esc(expr))
+end
 
 
 """
     @assert cond [text]
 
 Throw an [`AssertionError`](@ref) if `cond` is `false`. Preferred syntax for writing assertions.
-Message `text` is optionally displayed upon assertion failure.
-
-!!! warning
-    An assert might be disabled at various optimization levels.
-    Assert should therefore only be used as a debugging tool
-    and not used for authentication verification (e.g., verifying passwords),
-    nor should side effects needed for the function to work correctly
-    be used inside of asserts.
+Message `text` is optionally displayed upon assertion failure. Only active when julia is started
+in debug mode (`julia -g`).
 
 # Examples
 ```jldoctest
@@ -208,6 +212,7 @@ julia> @assert isodd(3) "What even are numbers?"
 ```
 """
 macro assert(ex, msgs...)
+    isdefined(@__MODULE__, :isdebug) && !(isdebug()) && return nothing
     msg = isempty(msgs) ? ex : msgs[1]
     if isa(msg, AbstractString)
         msg = msg # pass-through
diff --git a/base/exports.jl b/base/exports.jl
index 2c0c628eec866..bcbfc47536ebf 100644
--- a/base/exports.jl
+++ b/base/exports.jl
@@ -780,6 +780,7 @@ export
     atreplinit,
     exit,
     ntuple,
+    isdebug,
 
 # I/O and events
     close,
diff --git a/base/loading.jl b/base/loading.jl
index 776f06202e0b4..04eb221e0179e 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -1231,6 +1231,7 @@ function compilecache_path(pkg::PkgId, cache::TOMLCache)::String
         crc = _crc32c(unsafe_string(JLOptions().image_file), crc)
         crc = _crc32c(unsafe_string(JLOptions().julia_bin), crc)
         crc = _crc32c(get_preferences_hash(pkg.uuid, cache), crc)
+        crc = _crc32c(isdebug(), crc)
         project_precompile_slug = slug(crc, 5)
         abspath(cachepath, string(entryfile, "_", project_precompile_slug, ".ji"))
     end
@@ -1358,6 +1359,8 @@ function parse_cache_header(f::IO)
         end
         totbytes -= 4 + 4 + n2 + 8
     end
+    julia_debug = Bool(read(f, UInt8))
+    totbytes -= 1
     prefs_hash = read(f, UInt64)
     totbytes -= 8
     @assert totbytes == 12 "header of cache file appears to be corrupt"
@@ -1372,7 +1375,7 @@ function parse_cache_header(f::IO)
         build_id = read(f, UInt64) # build id
         push!(required_modules, PkgId(uuid, sym) => build_id)
     end
-    return modules, (includes, requires), required_modules, srctextpos, prefs_hash
+    return modules, (includes, requires), required_modules, srctextpos, prefs_hash, julia_debug
 end
 
 function parse_cache_header(cachefile::String; srcfiles_only::Bool=false)
@@ -1381,21 +1384,21 @@ function parse_cache_header(cachefile::String; srcfiles_only::Bool=false)
         !isvalid_cache_header(io) && throw(ArgumentError("Invalid header in cache file $cachefile."))
         ret = parse_cache_header(io)
         srcfiles_only || return ret
-        modules, (includes, requires), required_modules, srctextpos, prefs_hash = ret
+        modules, (includes, requires), required_modules, srctextpos, prefs_hash, julia_debug = ret
         srcfiles = srctext_files(io, srctextpos)
         delidx = Int[]
         for (i, chi) in enumerate(includes)
             chi.filename ∈ srcfiles || push!(delidx, i)
         end
         deleteat!(includes, delidx)
-        return modules, (includes, requires), required_modules, srctextpos, prefs_hash
+        return modules, (includes, requires), required_modules, srctextpos, prefs_hash, julia_debug
     finally
         close(io)
     end
 end
 
 function cache_dependencies(f::IO)
-    defs, (includes, requires), modules, srctextpos, prefs_hash = parse_cache_header(f)
+    defs, (includes, requires), modules, srctextpos, prefs_hash, julia_debug = parse_cache_header(f)
     return modules, map(chi -> (chi.filename, chi.mtime), includes)  # return just filename and mtime
 end
 
@@ -1410,7 +1413,7 @@ function cache_dependencies(cachefile::String)
 end
 
 function read_dependency_src(io::IO, filename::AbstractString)
-    modules, (includes, requires), required_modules, srctextpos, prefs_hash = parse_cache_header(io)
+    modules, (includes, requires), required_modules, srctextpos, prefs_hash, julia_debug = parse_cache_header(io)
     srctextpos == 0 && error("no source-text stored in cache file")
     seek(io, srctextpos)
     return _read_dependency_src(io, filename)
@@ -1496,7 +1499,7 @@ function stale_cachefile(modpath::String, cachefile::String, cache::TOMLCache)
             @debug "Rejecting cache file $cachefile due to it containing an invalid cache header"
             return true # invalid cache file
         end
-        modules, (includes, requires), required_modules, srctextpos, prefs_hash = parse_cache_header(io)
+        modules, (includes, requires), required_modules, srctextpos, prefs_hash, julia_debug = parse_cache_header(io)
         id = isempty(modules) ? nothing : first(modules).first
         modules = Dict{PkgId, UInt64}(modules)
 
@@ -1572,6 +1575,11 @@ function stale_cachefile(modpath::String, cachefile::String, cache::TOMLCache)
         end
 
         if isa(id, PkgId)
+            curr_debug = isdebug()
+            if julia_debug != curr_debug
+                @debug "Rejecting cache file $cachefile because julia debug mode does not match"
+                return true
+            end
             curr_prefs_hash = get_preferences_hash(id.uuid, cache)
             if prefs_hash != curr_prefs_hash
                 @debug "Rejecting cache file $cachefile because preferences hash does not match 0x$(string(prefs_hash, base=16)) != 0x$(string(curr_prefs_hash, base=16))"
diff --git a/doc/Makefile b/doc/Makefile
index 3bf710c6a4a48..afccffe8331f8 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -7,7 +7,7 @@ SRCDIR           := $(abspath $(dir $(lastword $(MAKEFILE_LIST))))
 JULIAHOME        := $(abspath $(SRCDIR)/..)
 SRCCACHE         := $(abspath $(JULIAHOME)/deps/srccache)
 include $(JULIAHOME)/Make.inc
-JULIA_EXECUTABLE := $(call spawn,$(build_bindir)/julia) --startup-file=no
+JULIA_EXECUTABLE := $(call spawn,$(build_bindir)/julia) --startup-file=no -g2
 
 .PHONY: help clean cleanall html pdf deps deploy
 
diff --git a/src/dump.c b/src/dump.c
index 287bf2d44701b..d6965aebbd45b 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -1124,6 +1124,14 @@ static int64_t write_dependency_list(ios_t *s, jl_array_t **udepsp, jl_array_t *
         }
         write_int32(s, 0); // terminator, for ease of reading
 
+        // Julia debug mode
+        jl_value_t *julia_debug = (jl_value_t*)jl_get_global(jl_base_module, jl_symbol("julia_debug"));
+        if (julia_debug) {
+            write_int8(s, jl_unbox_bool(julia_debug));
+        } else {
+            write_int8(s, 0);
+        }
+
         // Calculate Preferences hash for current package.
         jl_value_t *prefs_hash = NULL;
         if (jl_base_module) {
diff --git a/test/assert.jl b/test/assert.jl
new file mode 100644
index 0000000000000..312c17c8fda8e
--- /dev/null
+++ b/test/assert.jl
@@ -0,0 +1,60 @@
+# This file is run from test/misc.jl separately since it needs to run with `-g2`.
+using Test
+
+# test @assert macro
+@test_throws AssertionError (@assert 1 == 2)
+@test_throws AssertionError (@assert false)
+@test_throws AssertionError (@assert false "this is a test")
+@test_throws AssertionError (@assert false "this is a test" "another test")
+@test_throws AssertionError (@assert false :a)
+let
+    try
+        @assert 1 == 2
+        error("unexpected")
+    catch ex
+        @test isa(ex, AssertionError)
+        @test occursin("1 == 2", ex.msg)
+    end
+end
+# test @assert message
+let
+    try
+        @assert 1 == 2 "this is a test"
+        error("unexpected")
+    catch ex
+        @test isa(ex, AssertionError)
+        @test ex.msg == "this is a test"
+    end
+end
+# @assert only uses the first message string
+let
+    try
+        @assert 1 == 2 "this is a test" "this is another test"
+        error("unexpected")
+    catch ex
+        @test isa(ex, AssertionError)
+        @test ex.msg == "this is a test"
+    end
+end
+# @assert calls string() on second argument
+let
+    try
+        @assert 1 == 2 :random_object
+        error("unexpected")
+    catch ex
+        @test isa(ex, AssertionError)
+        @test !occursin("1 == 2", ex.msg)
+        @test occursin("random_object", ex.msg)
+    end
+end
+# if the second argument is an expression, c
+let deepthought(x, y) = 42
+    try
+        @assert 1 == 2 string("the answer to the ultimate question: ",
+                              deepthought(6, 9))
+        error("unexpected")
+    catch ex
+        @test isa(ex, AssertionError)
+        @test ex.msg == "the answer to the ultimate question: 42"
+    end
+end
diff --git a/test/errorshow.jl b/test/errorshow.jl
index 2d370d7f05246..f64902044a405 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -332,7 +332,7 @@ let undefvar
     @test err_str == "InterruptException:"
     err_str = @except_str throw(ArgumentError("not an error")) ArgumentError
     @test err_str == "ArgumentError: not an error"
-    err_str = @except_str @assert(false) AssertionError
+    err_str = read(`$(Base.julia_cmd()) -g2 -e 'try @assert false; catch e; showerror(stdout, e); end'`, String)
     @test err_str == "AssertionError: false"
 end
 
diff --git a/test/exceptions.jl b/test/exceptions.jl
index 7b8a54da2c6eb..67dbad17b7321 100644
--- a/test/exceptions.jl
+++ b/test/exceptions.jl
@@ -369,6 +369,8 @@ end
 end
 
 # issue #36527
+s = raw"""
+using Test
 function f36527()
     caught = false
     🏡 = Core.eval(Main, :(module asdf36527 end))
@@ -383,6 +385,8 @@ function f36527()
 end
 
 @test f36527()
+"""
+@test success(`$(Base.julia_cmd()) -g2 -e $s`)
 
 # accessing an undefined var in tail position in a catch block
 function undef_var_in_catch()
diff --git a/test/misc.jl b/test/misc.jl
index 920a03abdb520..425dc14a79487 100644
--- a/test/misc.jl
+++ b/test/misc.jl
@@ -3,64 +3,8 @@
 isdefined(Main, :FakePTYs) || @eval Main include("testhelpers/FakePTYs.jl")
 
 # Tests that do not really go anywhere else
-
-# test @assert macro
-@test_throws AssertionError (@assert 1 == 2)
-@test_throws AssertionError (@assert false)
-@test_throws AssertionError (@assert false "this is a test")
-@test_throws AssertionError (@assert false "this is a test" "another test")
-@test_throws AssertionError (@assert false :a)
-let
-    try
-        @assert 1 == 2
-        error("unexpected")
-    catch ex
-        @test isa(ex, AssertionError)
-        @test occursin("1 == 2", ex.msg)
-    end
-end
-# test @assert message
-let
-    try
-        @assert 1 == 2 "this is a test"
-        error("unexpected")
-    catch ex
-        @test isa(ex, AssertionError)
-        @test ex.msg == "this is a test"
-    end
-end
-# @assert only uses the first message string
-let
-    try
-        @assert 1 == 2 "this is a test" "this is another test"
-        error("unexpected")
-    catch ex
-        @test isa(ex, AssertionError)
-        @test ex.msg == "this is a test"
-    end
-end
-# @assert calls string() on second argument
-let
-    try
-        @assert 1 == 2 :random_object
-        error("unexpected")
-    catch ex
-        @test isa(ex, AssertionError)
-        @test !occursin("1 == 2", ex.msg)
-        @test occursin("random_object", ex.msg)
-    end
-end
-# if the second argument is an expression, c
-let deepthought(x, y) = 42
-    try
-        @assert 1 == 2 string("the answer to the ultimate question: ",
-                              deepthought(6, 9))
-        error("unexpected")
-    catch ex
-        @test isa(ex, AssertionError)
-        @test ex.msg == "the answer to the ultimate question: 42"
-    end
-end
+assert_file = joinpath(@__DIR__, "assert.jl")
+@test success(`$(Base.julia_cmd()) -g2 $assert_file`)
 
 let # test the process title functions, issue #9957
     oldtitle = Sys.get_process_title()
@@ -770,9 +714,9 @@ end
 
 @kwdef struct TestInnerConstructor
     a = 1
-    TestInnerConstructor(a::Int) = (@assert a>0; new(a))
+    TestInnerConstructor(a::Int) = (a>0 || error(); new(a))
     function TestInnerConstructor(a::String)
-        @assert length(a) > 0
+        length(a) > 0 || error()
         new(a)
     end
 end
@@ -780,9 +724,9 @@ end
 @testset "@kwdef inner constructor" begin
     @test TestInnerConstructor() == TestInnerConstructor(1)
     @test TestInnerConstructor(a=2) == TestInnerConstructor(2)
-    @test_throws AssertionError TestInnerConstructor(a=0)
+    @test_throws ErrorException TestInnerConstructor(a=0)
     @test TestInnerConstructor(a="2") == TestInnerConstructor("2")
-    @test_throws AssertionError TestInnerConstructor(a="")
+    @test_throws ErrorException TestInnerConstructor(a="")
 end
 
 const outsidevar = 7
@@ -819,7 +763,7 @@ end
 
 @testset "Pointer to unsigned/signed integer" begin
     # assuming UInt and Ptr have the same size
-    @assert sizeof(UInt) == sizeof(Ptr{Nothing})
+    @test sizeof(UInt) == sizeof(Ptr{Nothing})
     uint = UInt(0x12345678)
     sint = signed(uint)
     ptr = reinterpret(Ptr{Nothing}, uint)
diff --git a/test/precompile.jl b/test/precompile.jl
index 92ff419bf5997..4373e4b811fb9 100644
--- a/test/precompile.jl
+++ b/test/precompile.jl
@@ -901,4 +901,73 @@ let
     end
 end
 
+# Debug mode
+let
+    tmp = mktempdir()
+    try
+        cd(tmp) do
+            pkg_content(mod) = """
+            """
+
+            write("Project.toml", """
+                  [deps]
+                  A = "065497a9-3da1-45c2-901d-78aba5544f04"
+                  B = "d52a13bc-ce4c-4a58-a416-e1c8b2d677de"
+                  """)
+
+            write("Manifest.toml", """
+                    [[A]]
+                    deps = ["B"]
+                    path = "A"
+                    uuid = "065497a9-3da1-45c2-901d-78aba5544f04"
+
+                    [[B]]
+                    path = "B"
+                    uuid = "d52a13bc-ce4c-4a58-a416-e1c8b2d677de"
+                    """)
+
+            mkpath("A/src/")
+            write("A/src/A.jl", """
+                module A
+                    using B
+                    const is_debug = isdebug()
+                    maybe_assert() = @assert false
+                end
+                """)
+
+            mkpath("B/src/")
+            write("B/src/B.jl", """
+                module B
+                    const is_debug = isdebug()
+                    maybe_assert() = @assert false
+                end
+                """)
+
+            s = """
+                using Test
+                using A
+                @test A.is_debug == true
+                @test A.B.is_debug == true
+                @test_throws AssertionError A.maybe_assert()
+                @test_throws AssertionError A.B.maybe_assert()
+            """
+            @test success(Cmd(`$(Base.julia_cmd()) --project -g2 -e $s`; env = ["JULIA_DEPOT_PATH"=>tmp]))
+
+            s = """
+                using Test
+                using A
+                @test A.is_debug == false
+                @test A.B.is_debug == false
+                @test A.maybe_assert() === nothing
+                @test A.B.maybe_assert() === nothing
+            """
+            @test success(Cmd(`$(Base.julia_cmd()) --project -e $s`; env = ["JULIA_DEPOT_PATH"=>tmp]))
+        end
+    finally
+        rm(tmp; recursive=true)
+    end
+end
+
+
+
 end # !withenv